I hate it when I try to do something I think is simple and then I fail.

Okay, how the heck do I install a saddle?! New saddle arrived today. Got the old one off, put the new one on, but I can't seem to tighten the seat clamp without the thing moving up and pointing up in the air.

I have a two-bolt post.

I've tried tightening them both back and forth, and no luck. What am I doing wrong?