I tested the model on a 16.3 version and it works, as you can see on attachment...
the original model was developed in orcad 9.x or 10.x, can't remeber actually, so Orcad 16.x just "convert" it...
probably a problem in the conversion...
try the attached one (already converted in 16.3, so closer to your version)...
Vincenzo
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