[WD20] Process Property not available for Table Column

Hi,
I can't associate a procedure ("LP_Change") with the entry/exit process of the columns (i.e. "COL_Model") of a table ("TABLE_Size")

My code:

[Initializing TABLE_Size]
TABLE_Size.COL_Model..Process[trtExit] = "LP_Change"

It generates this fatal error:
WL call:
Process of Initializing TABLE_Size line1, thread 0

What Happened?
This process is not available for this control

Error code: 1018
Level: fatal error (EL_FATAL)


Is it a normal behaviour??
Thanks
Dann