MTD TurfPro 17.5hp OVHD needs help?

I replaced the variable speed belt that attaches from the engine to the transmission. However, now when I shift gears it will not actually do anything. The shifter shifts easilly but doesn't engage. It's like I'm stuck in 1st gear in forward and reverse. I've adjusted the speed control link with no progress. I adjusted the neutral adjustment rod. All the springs and rods seem to be in right. I need help am I missing something.