IF OR ISERROR problem

Okay, my formula doesn't work, and I'm at a loss. Here's what I want to do:

IF O2 minus J2 is an error (because there's no values in O2 or J2), OR if O2 minus J2 is Zero or less, don't show anything. Otherwise, show the results of O2-J2. Code is below, but I've got something hosed and can't figure out what. Any help would be appreciated.

=IF((OR(ISERROR(O2-J2),O2-J2<=0)),"",O2-J2)