When you attach the cable between your tab and the PC, is the tab at the main menu unlocked? I have a totally different device but it won't attach if its screen-locked when the connection is made.
Once you attach the tablet to the PC via USB, do you get a failure message? Does the PC respond at all, even beeping? Have you opened Explorer and looked in My Computer? I ask that because, with my tablet, the tablet shows up as a storage device and I have to navigate (on the PC) to the photo storage on that device.
Or are you using PC software that was provided by Samsung, which would be a different kettle of figurative fish?
A little more detail can help us resolve your problem.