Problem with message control for purchasing orders

Hi,

If I create an purchasing order I get the following error message "No message generated for output of purchasing document".

But the customizing for the condition type seems to be ok and if I have a look at the message analysis I can see that a valid output condition has been found.

System response: An output proposal is created.

Access Message Description

10 541 Output found

Purchasing Doc. Type ZXXX

Purch. Organization 0001

Vendor 0000004101

So what could be the problem that the messages can not be created for the purchasing document??

Thanks in advance for any help.