short dump : help required

I get a short dump when cpmparing two currency fields as follows :

DATA: loc_totpy(25) TYPE c.

FIELD-SYMBOLS : <totpayment> TYPE ANY.

READ TABLE input WITH KEY 'REGUH-RBETR'.

IF sy-subrc = 0.

ASSIGN input-value TO <totpayment> .

loc_totpy = <totpayment>.

ENDIF.

-

> IF loc_totpy gt int_zchqlimit-zsiglimit.

sig = int_zchqlimit-zsighigh.

SHORT DUMP OCCOURS HERE.....

zsiglimit = curreny field (length = 13, decimal=2)

zsighigh = CHAR (length 70)

Any indication of the problem