We just redone our plumbing in the bathroom and now our toiket won't flush

More details please! Please explain what you have done to your bath. Does the toilet back up? Does it not fill with water? Does everything else worked? Can you give me more details? Back to you, Tom

When we hook the pipe together from the tub to the vent pipe, the toilet won't flush. When we unhook it, it flushes. What donwe do?
This is a typical installation. Have you connected your drainage like the illustration? Back to you, Tom