It seems like an authorization issue.
Please check whether "SAP_FIN_VENDOR_BAL_APP" is given to the user id in backend
and "SAP_SFIN_BCR_PAYABLES_CLERK" is given in the front end.
If still getting error, Please switch on the traces in ST01 tcode and find out the required missing authorizations.
Also check "/iwfnd/error_log" tcode in front end for more details on the error.
regards,
Sarbjeet Singh