APEXP Workflow error in r12

Hello

This is on r12.1.3 -iExpense

We are facing a issue with I Expense Workflow.

When we submit any Expense report , the workflow fails at the node 'Pending Manager Approval' with the following error:

Failed Activity Build Receipt Information For Approval Letter

Activity Type Function

Error Name -6502

Error Message ORA-06502: PL/SQL: numeric or value error: character string buffer too small

Error Stack Wf_Engine_Util.Function_Call(AP_WEB_EXPENSE_WF.CALLBACKFUNCTION, APEXP, 311213, SET_CTX) Wf_Engine_Util.Execute_Selector_Function(APEXP, 311213, SET_CTX) Wf_Engine_Util.Function_Call(AP_WEB_EXPENSE_WF.BUILDMANAGERAPPRVLMESSAGE, APEXP, 311213, 193494, RUN)

But when i use the 'Retry' option in Workflow manager , it completes fine.