Diagnosis
Possible causes for the error are listed in the check log.

Procedure
However, since these messages are often of a technical nature, thiscould also be a possible cause:
Message: Entry in field not allowed...
In this case, the field status control for the field is probablyset to Hidden. Check your field status settings in Customizing inthe Define Field Selection String IMG activity.
Important
After making changes in Customizing, you have to start the processingtransaction again for the new settings to take effect.