Creating an exit for a sustitution rule in FI

Hi All,

I'm creating an exit for a sustitution rule in FI.

The code abap i have put in is..

*...................

}   INSERT

exits-name  = 'U206'.

exits-param = c_exit_param_field.

exits-title = text-206.            "Sostituisce il livello CM nelle rich.di pagamento

APPEND exits.

............

FORM u206.

DATA: livcm LIKE bseg-fdlev.

livcm = 'FZ'.

if bkpf-blart ='ZP'AND BSEG-BSCHL = '25'.

MOVE livcm TO bseg-fdlev.

ENDIF.

ENDFORM.

In the subsitution rule, as prerequisite, I've filled in:

BKPF-BLART = 'ZP'

When I execute the t.code FIBLAPOP, SAP gives me the error message

"Error run time PERFORM_TOO_MANY_PARAMETERS"

Could anyone help me? The exit shuold work only when I execute t.code FIBLAPOP. But if I set as prerequisite

SYST-TCODE = 'FIBLAPOP', the substitution doesn't work.

Thanks for your hepl.

G.