Getting critical program error when calling a Function Module

Hi Experts,

I am getting a critical program error when calling a new function module from a class. The FM just passes budget number and year and concatenates into a new string. When I debug it runs into a CATCH cx_root INTO l_r_root_ line but i am surprised as its the simplest of the FM. I have also made entry in table RSPLF_FDIR for this FM.