getCookie throws IllegalStateException

Hi,

When I try to call node.getCookie(), it throws following Error
java.lang.IllegalStateException
at org.netbeans.modules.enode.FactoryWrapper.clazz(FactoryWrapper.java:164)
at org.netbeans.modules.enode.FactoryWrapper.instantiate(FactoryWrapper.java:177)
at org.netbeans.modules.enode.FactoryWrapper.create(FactoryWrapper.java:67)
at org.netbeans.modules.enode.ExtensibleLookupImpl.beforeLookup(ExtensibleLookupImpl.java:153)
at org.openide.util.lookup.ProxyLookup.lookup(ProxyLookup.java:177) at org.netbeans.api.enode.ExtensibleLookup.lookup(ExtensibleLookup.java:71)
at org.openide.util.lookup.ProxyLookup.lookup(ProxyLookup.java:182) at org.openide.nodes.Node.getCookie(Node.java:687)
at org.openide.nodes.AbstractNode.getCookie(AbstractNode.java:731)

could anyone please help me on this ?
Thanks in advance
+Shagi