Getting ORA-06502: PL/SQL: numeric or value error: character to number conversion error ERP

Summary:

Hi I m using below query as subquery for a report but it is giving numeric or value error: character to number conversion error

What changes can be done to prevent this error. I tried adding to_char to all the elements bt the issue persists

Query--

,(select SUBSTR(attribute4,INSTR(attribute4,'-')+1,LENGTH(attribute4))

      from apps.GME_BATCH_HEADER

      where organization_id=ood.organization_id

      and batch_no= mln.lot_number

      ) GMID

Organization ID in both tables has NUMBER data type

BATCH_NO -- VARCHAR2(32)

LOT_NUMBER--VARCHAR2(80)

ATTRIBUTE4 VARCHAR2(240)

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