For comparing two sets, I would usually suggest something more likeevalb(rep=$REP);
instead of the default code. However in this case, Maple doesn't always try to equate an exact number (i.e. fraction) with a floating point number unless you force it to.
Therefore, instead of the evalb line, try this line to force direct comparison between each set element:is(rep = $REP) and is(rep = $REP);