Channel Revenue - Offer approval - using Custom function -- workflow stuck with error

Channel Revenue Management - Offer approval - using Custom function to fetch requestor's manager as approver.

When approval is requested -- workflow AMSAPRV (AMS Marketing Approvals) triggered workflow process.

1) Process Name: Budget Line Approval -- Custom function is getting the approver -- a notification is sent out -- responses are processed as expected. 

2) Process Name: Marketing Approval Process --> workflow process is getting stuck with error at node "Get Approver Details"

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Failed Activity

Get Budget Line Approver Details

Error: ORA-01403: no data found ORA-01403: no data found ORA-01403: no data found

Error stack; AMS_APPROVAL_PVT.Get_Line_Approver_Details : (AMSAPRV, 264166_OFFR12204169, 286810) Wf_Engine_Util.Function_Call(AMS_APPROVAL_PVT.GET_LINE_APPROVER_DETAILS, AMSAPRV, 264166_OFFR12204169, 286810, RUN)