Added custom field in PR Item Overview is disabled, cannot be changed.

Hi experts,

My task was to add a custom field Release Date in Item Overview of Purchase Request in Tcodes: ME51N, ME53N and ME54N. I've read from different discussions that I can use user exit MEREQ001. So after reading discussions and the documentation here is what i did:

• Create project/user exit in CMOD and assigned MEREQ001 as enhancement.
• Added custom field ZZRECDT (Received Date) at include table CI_EBANDB
• Write code to Function exit EXIT_SAPLMEREQ_001 & EXIT_SAPLMEREQ_003 to get & set values
• Activate the project/user exit

My problem now is that the custom field is now appears in Item overview but is disabled in all tcodes (ME51N, ME53N and ME54N). Did I missed something?

Regards,

Rod