diff --git a/library/src/main/java/org/mustangproject/Product.java b/library/src/main/java/org/mustangproject/Product.java
index 83cf4543..cc19932d 100644
--- a/library/src/main/java/org/mustangproject/Product.java
+++ b/library/src/main/java/org/mustangproject/Product.java
@@ -23,9 +23,9 @@ import java.util.Map;
 
 public class Product implements IZUGFeRDExportableProduct {
 	protected String unit, name, sellerAssignedID, buyerAssignedID;
-	protected String description="";
-	protected String taxExemptionReason=null;
-	protected String taxCategoryCode=null;
+	protected String description = "";
+	protected String taxExemptionReason = null;
+	protected String taxCategoryCode = null;
 	protected BigDecimal VATPercent;
 	protected boolean isReverseCharge = false;
 	protected boolean isIntraCommunitySupply = false;
@@ -61,8 +61,6 @@ public class Product implements IZUGFeRDExportableProduct {
 		});
 
 
-
-
 		nodeMap.getAsString("SellerAssignedID").ifPresent(this::setSellerAssignedID);
 		nodeMap.getAsString("BuyerAssignedID").ifPresent(this::setBuyerAssignedID);
 		nodeMap.getAsString("Name").ifPresent(this::setName);
@@ -155,7 +153,7 @@ public class Product implements IZUGFeRDExportableProduct {
 	 * @param taxExemptionReasonText String e.g. Kleinunternehmer gemäß §19 UStG https://github.com/ZUGFeRD/mustangproject/issues/463
 	 * @return fluent setter
 	 */
-	public Product setTaxExemptionReason(String  taxExemptionReasonText) {
+	public Product setTaxExemptionReason(String taxExemptionReasonText) {
 		taxExemptionReason = taxExemptionReasonText;
 		return this;
 	}
@@ -177,7 +175,7 @@ public class Product implements IZUGFeRDExportableProduct {
 	 * @param code e.g. S (normal tax), Z=zero rated,  E (e.g. small business) or K (intrra community supply) see also https://github.com/ZUGFeRD/mustangproject/issues/463
 	 * @return fluent setter
 	 */
-	public Product setTaxCategoryCode(String  code) {
+	public Product setTaxCategoryCode(String code) {
 		taxCategoryCode = code;
 		return this;
 	}
@@ -304,18 +302,22 @@ public class Product implements IZUGFeRDExportableProduct {
 	 * @return fluent setter
 	 */
 	public Product setVATPercent(BigDecimal VATPercent) {
-		this.VATPercent = VATPercent;
+		if (VATPercent == null) {
+			this.VATPercent = BigDecimal.ZERO;
+		} else {
+			this.VATPercent = VATPercent;
+		}
 		return this;
 	}
 
 	@Override
 	public String getCountryOfOrigin() {
-	    return this.countryOfOrigin;
+		return this.countryOfOrigin;
 	}
 
 	public Product setCountryOfOrigin(String countryOfOrigin) {
-	    this.countryOfOrigin = countryOfOrigin;
-	    return this;
+		this.countryOfOrigin = countryOfOrigin;
+		return this;
 	}
 
 	@Override
@@ -328,16 +330,16 @@ public class Product implements IZUGFeRDExportableProduct {
 	}
 
 	public Product setAttributes(Map<String, String> attributes) {
-	    this.attributes.clear();
+		this.attributes.clear();
 		if (attributes != null) {
 			this.attributes.putAll(attributes);
 		}
-	    return this;
+		return this;
 	}
 
-	public Product addAttribute(String name, String value ) {
-	    this.attributes.put(name, value);
-	    return this;
+	public Product addAttribute(String name, String value) {
+		this.attributes.put(name, value);
+		return this;
 	}
 
 	@Override
diff --git a/library/src/main/java/org/mustangproject/ZUGFeRD/LineCalculator.java b/library/src/main/java/org/mustangproject/ZUGFeRD/LineCalculator.java
index f3e8aa2d..c44f29ee 100644
--- a/library/src/main/java/org/mustangproject/ZUGFeRD/LineCalculator.java
+++ b/library/src/main/java/org/mustangproject/ZUGFeRD/LineCalculator.java
@@ -44,7 +44,13 @@ public class LineCalculator {
 		BigDecimal multiplicator = vatPercent.divide(BigDecimal.valueOf(100));
 		priceGross = currentItem.getPrice(); // see https://github.com/ZUGFeRD/mustangproject/issues/159
 		price = priceGross.subtract(allowance).add(charge);
-		itemTotalNetAmount = currentItem.getQuantity().multiply(getPrice()).divide(currentItem.getBasisQuantity(), 18, RoundingMode.HALF_UP)
+
+		BigDecimal quantity=BigDecimal.ZERO;
+		if ((currentItem!=null)&&(currentItem.getQuantity()!=null)) {
+			quantity=currentItem.getQuantity();
+		}
+
+		itemTotalNetAmount = quantity.multiply(getPrice()).divide(currentItem.getBasisQuantity(), 18, RoundingMode.HALF_UP)
 				.subtract(allowanceItemTotal).setScale(2, RoundingMode.HALF_UP);
 		itemTotalVATAmount = itemTotalNetAmount.multiply(multiplicator);
 
diff --git a/library/src/main/java/org/mustangproject/ZUGFeRD/TransactionCalculator.java b/library/src/main/java/org/mustangproject/ZUGFeRD/TransactionCalculator.java
index 0b7ca5e3..8740e157 100644
--- a/library/src/main/java/org/mustangproject/ZUGFeRD/TransactionCalculator.java
+++ b/library/src/main/java/org/mustangproject/ZUGFeRD/TransactionCalculator.java
@@ -167,7 +167,11 @@ public class TransactionCalculator implements IAbsoluteValueProvider {
 		final String vatDueDateTypeCode = trans.getVATDueDateTypeCode();
 
 		for (IZUGFeRDExportableItem currentItem : trans.getZFItems()) {
-			BigDecimal percent = currentItem.getProduct().getVATPercent();
+			BigDecimal percent = null;
+			if (currentItem.getProduct()!=null)
+			{
+				percent=currentItem.getProduct().getVATPercent();
+			}
 			if (percent != null) {
 				LineCalculator lc = new LineCalculator(currentItem);
 				VATAmount itemVATAmount = new VATAmount(lc.getItemTotalNetAmount(), lc.getItemTotalVATAmount(),
diff --git a/library/src/main/java/org/mustangproject/ZUGFeRD/ZUGFeRDInvoiceImporter.java b/library/src/main/java/org/mustangproject/ZUGFeRD/ZUGFeRDInvoiceImporter.java
index 99a7ba9e..5f49b6dc 100644
--- a/library/src/main/java/org/mustangproject/ZUGFeRD/ZUGFeRDInvoiceImporter.java
+++ b/library/src/main/java/org/mustangproject/ZUGFeRD/ZUGFeRDInvoiceImporter.java
@@ -556,7 +556,10 @@ public class ZUGFeRDInvoiceImporter {
 			// UBL...
 			number = extractString("//*[local-name()=\"Invoice\"]/*[local-name()=\"ID\"]").trim();
 			typeCode = extractString("//*[local-name()=\"Invoice\"]/*[local-name()=\"InvoiceTypeCode\"]").trim();
-			issueDate = new SimpleDateFormat("yyyy-MM-dd").parse(extractString("//*[local-name()=\"Invoice\"]/*[local-name()=\"IssueDate\"]").trim());
+			String issueDateStr = extractString("//*[local-name()=\"Invoice\"]/*[local-name()=\"IssueDate\"]").trim();
+			if (issueDateStr.length()>0) {
+				issueDate = new SimpleDateFormat("yyyy-MM-dd").parse(issueDateStr);
+			}
 			String dueDt = extractString("//*[local-name()=\"Invoice\"]/*[local-name()=\"DueDate\"]").trim();
 			if (dueDt.length() > 0) {
 				dueDate = new SimpleDateFormat("yyyy-MM-dd").parse(dueDt);
@@ -775,7 +778,7 @@ public class ZUGFeRDInvoiceImporter {
 
 		}
 
-		zpp.setDueDate(dueDate).setDeliveryDate(deliveryDate).setIssueDate(issueDate).setSender(new TradeParty(SellerNodes)).setRecipient(new TradeParty(BuyerNodes)).setNumber(number).setDocumentCode(typeCode);
+		zpp.setIssueDate(issueDate).setDueDate(dueDate).setDeliveryDate(deliveryDate).setSender(new TradeParty(SellerNodes)).setRecipient(new TradeParty(BuyerNodes)).setNumber(number).setDocumentCode(typeCode);
 
 		if ((directDebitMandateID != null) && (IBAN != null)) {
 			DirectDebit d = new DirectDebit(IBAN, directDebitMandateID);