It looks like when you changed the input to a select you also changed it from name="Category1" to name="Category".... change the name back to Category1 on the search page and that should fix the problem.
Your friends over here at WebAssist! These Dreamweaver extensions will assist you in building unlimited, custom websites.
These out-of-the-box solutions provide you proven, tested applications that can be up and running now. Build a store, a gallery, or a web-based email solution.