MSCM item number length?

We just went live on MSCM (10.1.4.5) and we have item numbers in Lawson that are 3 and 4 characters long - but our handhelds won't scan them. Is there a setting for item number length that anyone can share or is there some config that the handheld would need to recognize a number that short as being within scope for scanning? Any suggestions appreciated, thanks!