Ok when you connect your device to the pc in 'charge mode' does the computer recognise it and say Android ADB Interface?
If so then your doing the right thing, if not reinstall the drivers
1. Click on Start and right-click on Computer. Select Properties and go to the Device Manager.
2. Under Other Devices, you should see the Android 1.0 device. Right-click on Android 1.0 and click on Update Driver Software. Browse your computer for the driver software and select the Android modified USB drivers folder that you extracted on your desktop.
OR
Try to use unrEVOked version 3.21 or 3.14, sorry but i think the version i used was 3.21, (the pc i used hasnt been working for ages and all my rooting tools were on there)
OR
Have you uninstalled HTC Sync??