Inventor - Bearing Flat iMates

I’m following the Clawbot assembly for Inventor from the VEX website, but I just canno get the iMates on the bearing flat to snap into place on the rails. I have been successful with using iMates to constrain 8-32’s with nuts and structure to structure, and 8-32/nut component to structure, but once I get to the part of the video that shows iMating the bearing flats to the rail, I can’t get this to work on my Inventor. I click the Alt button then click on the the bearing flat iMate while still holding the Alt button. I then start to move the the bearing flat over while releasing the Alt button, but no iMates on the rail turns red for me to mate it. Any advice?

Does the piece of metal have imates on it?

I have been having the same problem. the bearing flat and the rail both have iMates. The bearing flat will mate but never where you want it to. This bearing flat is from the Inventor 2013 KOP found in Appendix 9 of Vex curriculum. The bearing flat from the Imperial KOP from Chapter 4 mates fine. I have been using that one.

I suggest using the community parts library made by @LegoMindstormsmaniac

That should do the trick.