imgscan.ocx

I’m using the imgscan.ocx in a windows 2000 service pack4 and i can’t initialize the scanner i use the method ScannerAvailable() and it returns false. I’ve tried to read something about it and it seems i don’t have the twain software?!?! i can use the method ShowSelectScanner() and it shows the scanner that i have in my pc (hp scanjet 3500c). Can anyone help me? thanks