Posting Preview Error forces uncomplete Posting

try this:
1.) Insert Gen. Jnl. Line with wrong sign, e.g. Cust. Invoice with neg. Amount
2.) Start "Posting Preview" ==>>> an Error will be shown
3.) correct sign
4.) post the Line immediatly (without "Posting Preview")
The result is:
- Message ("Nothing to post")
- Gen. Jnl. Line still exists
- Entries have been generated: G/L Entries, Vat Entry, Customer Entry, Det. Customer Entry, ...
- There is no "G/L Register" ! ! !
- Next try of Posting the Line results to an Error (Customer Invoice alresdy exists)

The reason is: In case if Preview-Error CU 19 gets no "End of Preview"-Information. But how can I fix it?