Messages in WPLST not displaying in POS monitor...

Hello Experts,

I am using FM 'VWWS_STORD_WRITE_WPLST' to write the error messages in my itab to POS

interface monitor(WPER). Below is my code:

CALL FUNCTION 'VWWS_STORD_WRITE_WPLST'
      TABLES
        i_wplst       = g_prot_wplst.

g_prot_wplst contains records form table WPLST. But when I check in WPER for the given idoc

there are no error messages displayed.