Cannot create Issue with Java API

I want to copy an issue with this code:

			MutableIssue copiedIssue= ComponentAccessor.getIssueFactory().cloneIssueWithAllFields(issue);
			try {
			} catch (CreateException e) {
				throw new RuntimeException(e);

I get this error Message:

java.lang.RuntimeException:com.atlassian.jira.workflow.WorkflowException: An unknown exception occured executing Validator com.atlassian.jira.workflow.SkippableValidator@4b24c667: root cause: java.lang.NullPointerException

This works very fine until now…
I just changed somerwhere else the code with active objects but this has no influence on this part of the code and is also not executed(i deleted everything and rebuild it but nothing helped).