diff --git a/src/helma/objectmodel/db/NodeManager.java b/src/helma/objectmodel/db/NodeManager.java
index 1cdef7cc..380c5c60 100644
--- a/src/helma/objectmodel/db/NodeManager.java
+++ b/src/helma/objectmodel/db/NodeManager.java
@@ -274,18 +274,19 @@ public final class NodeManager {
 	if (node != null && node.getState() != Node.INVALID) {
 	    // check if node is null node (cached null)
 	    if (node.isNullNode ()) {
-	        if (node.created() < rel.otherType.getLastDataChange () ||
-	            node.created() < rel.ownType.getLastTypeChange())
+	        if (node.created < rel.otherType.getLastDataChange () ||
+	            node.created < rel.ownType.getLastTypeChange())
 	            node = null; //  cached null not valid anymore
-	    } else if (!rel.virtual && !rel.usesPrimaryKey ()) {
+	    } else if (!rel.virtual) {
 	        // apply different consistency checks for groupby nodes and database nodes:
 	        // for group nodes, check if they're contained
 	        if (rel.groupby != null) {
 	            if (home.contains (node) < 0)
 	                node = null;
 	        // for database nodes, check if constraints are fulfilled
-	        } else if (!rel.checkConstraints (home, node)) {
-	            node = null;
+	        } else if (!rel.usesPrimaryKey ()) {
+	            if (!rel.checkConstraints (home, node))
+	                node = null;
 	        }
 	    }
 	}