SAPF150D-Dunning Notice Print - With Update of Line Items and Master Record

When I am running this program SAPF150D(Dunning Notice Print - With Update of Line Items and Master Records) with a variant containing run date, runc id, update mode, pimmed & pcount; the job is failing to execute. It is giving message like,

"The field symbol is no longer assigned because there was an attempt makde previously in a Unicode program to set the field symbol using ASSIGN with offset and/or length specification. Here, the memory addressed by the offset/length specification was not within the allowed area."

"GETWA_NOT_ASSIGNED_RANGE" "SAPF150D" or "F150DFS0" "SORTFELDER_ERMITTELN"