Trailing Sign in Loader

From: Vorname Name <Vorname.Name_at_pcm.bosch.de>
Date: Sun, 11 Jul 1999 20:39:21 +0200
Message-ID: <7maoef$qpj$1@news.fr.internet.bosch.de>

Does anybody know, how to solve this problem: I have a flat file with data to be loaded in an oracle table. One field in the record is a number with trailing sign - but space when positive
Example
000020
000543-
000343

I tried it with the following.
QTY position (73:86) char "TO_NUMBER(:QTY,'999999S')" The result for minus values is ok. The plus values are rejected with the following message:
ORA-01722: invalid number Received on Sun Jul 11 1999 - 13:39:21 CDT