Diagnosis
You changed the system proposal for the fields of a physical pool, buta physical pool has a fixed structure.
A pool must have exactly two key fields with the names TABNAME (for thename of the logical pooled table) and VARKEY (the key fields of thelogical pooled table are stored as a string here).

Procedure
Set the definition of the physical pool back to the proposed structure.You have to delete the key field which you inserted.