how long is the amplicon ?

Very hard to problem solve with the given information, need to know more specifics, namely sequence of amplicon (self complimentary combinations, etc), predicted melting curve temperature and reaction conditions (salt concentrations, gradients, etc). Correct me if i am wrong, but the AB7500 is an antibody not DNA/RNA so how are you approaching the molecular beacon assay? A little more specific information would help greatly problem solving.

Thanks for your attention. The AB7500 is an Applied Biosystem RT PCR instrument. The amplicon is 280 bp, the molecular beacon probe is 23 bp (not including the hairpin extensions).  The TM of the probe/complement is 69C as calculated on umelt and as run on the AB7500 against the complementary oligo. 

Saying it another way, the melt curve is near ideal when tested against a complementary oligo in the same conditions as the amplification. The amplicon is a single clear band of the right size when examined on a gel. The probe clearly hybridizes with the amplicon as seen by an increase in fluorescence through PCR cycles, yet when the probe-amplicon then are run through a temperature gradient from 40-90C to melt the probe-amplicon complex the fluorescence either dips slightly but stays higher than a no template control or at the same level of the last round of the PCR cycle. I've designed a similar probe around the same sequence but lowered it's melting temperature but see the same results. 

Thanks, Aaron.