I tried to create a new network dataset (geodatabase-based) but failed. Below is what I did (I am using ArcGIS 9.3.1). 1. Start ArcCatalog. 2. Click Tools and click Extensions. 3. Check Network Analyst. 4. Click Close. 5. Navigate to the feature dataset location in the Catalog tree. 6. Right-click an existing feature dataset (there are two feature classes, one is a point, the other street centerlines) point to New, now comes the problem, Network Dataset is gray. I am not allowed start the wizard to create a new network dataset. Any suggestions?