Diagnosis
The function code field (OK code field) has not been defined on thisscreen. If the user selects an application function (not a systemfunction), the system usually provides it in the function code field(OK code field) as well as in SY-UCOMM. This is no longer possible.

System Response
The system is unable to inform the application of the current functioncode. The application should not use field SY_COMM. This field alwayscontains the code of the last function chosen, which is not alwaysidentical to the application-relevant code.

Procedure
You should always define a field for the function code on every screen.The Screen Painter always proposes such a field (OK category), you onlyneed to assign a name and include the definition in the ABAP program.