ADS 2008 Simulation Error

Created a stepped-impedence LPF in ADS Momentum and am now using it as part of a larger circuit in ADS Schematic. The simulation won't start due to the error below, however, if I remove the Momentum component, simulation completes with no errors whatsoever.

What could be the cause of this error?

Any help would be greatly appreciated!!!


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Simulation / Synthesis Messages

Error detected by hpeesofsim during analysis.
Could not find transient or envelope analysis component for cosimulation
of circuit with `filterMOM_1' and its neighbors

Status / Summary


hpeesofsim (*) 331.200 May 6 2008 (built: 05/06/08 00:26:15)
Copyright Agilent Technologies, 1989-2008.

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Simulation finished with errors.
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Resource usage:
Total stopwatch time: 0.19 seconds.
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Simulation terminated due to error.
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