Bug: The ITopologyGraph interface has an incorrect signature for hitTestSelection method
** This issue is addressed in ArcGIS 9.0 Service Pack 2 (SP2) **
The 'hitElement' argument to the hitTestSelection method of ITopologyGraph is of an incorrect type. Currently, the signature reads that the expected object type for this parameter is to be an ITopologyElement, but it is should be an empty, one-dimensional ITopologyElement array ( ITopologyElement ).
The hitTestSelection method call should to populate this empty array with the results.
Click on the link in Related Information below and download Service Pack 2, if necessary. **