ORA-06502: PL/SQL: numeric or value error

Dear all,
please see the below error for oracle reports in EBS 11.5.10.2 and database 9.2.0.6 ...

+---------------------------------------------------------------------------+
Purchasing: Version : 11.5.0

Copyright (c) 1979, 1999, Oracle Corporation. All rights reserved.

EMRI_PO_PRINT module: EMRI Purchase Order Print Report
+---------------------------------------------------------------------------+

Current system time is 04-APR-2012 07:59:01

+---------------------------------------------------------------------------+


+-----------------------------
| Starting concurrent program execution...
+-----------------------------

Arguments
------------
P_PO_NUMBER='1655.5'
P_ORG_ID='183'
------------

 Current NLS_LANG and NLS_NUMERIC_CHARACTERS Environment Variables are :
American_America.US7ASCII

'.,'

REP-1401: 'cf_contact_emailformula': Fatal PL/SQL error occurred.
ORA-06502: PL/SQL: numeric or value error


Report Builder: Release 6.0.8.25.0 - Production on Wed Apr 4 07:59:01 2012

(c) Copyright 1999 Oracle Corporation.  All rights reserved.

Enter Username: 
+---------------------------------------------------------------------------+
Start of log messages from FND_FILE
+---------------------------------------------------------------------------+
+---------------------------------------------------------------------------+
End of log messages from FND_FILE
+---------------------------------------------------------------------------+
Program exited with status 1
Concurrent Manager encountered an error while running Oracle*Report for your concurrent request 1784112.

Review your concurrent request log and/or report output file