Any CPU

Could not load file or assembly '<name>' or one of its dependencies. An attempt was made to load a program with an incorrect format.

Ran into the above error, found this post.  Changed from x86 to Any CPU, and it worked!

Microsoft SQL Reporting - Repeating headers on new pages

This is something I've battled for years.

I finally figured it out this week.

You need to select your tablix, go to the right of column groups, select the down arrow, check "Advanced Mode", select the static member from "Row Groups", if you have more than one, look for the one that selects the first cell in your header row ("WO #" in my case), make the properties window (hotkey F4) shows "KeepWithGroup" as "After".  That means you have the proper object selected.  Now, change "RepeatOnNewPage" to "True" and do the same for "FixedData". 

That should do it.  Seems simple once you know, but man is it had to find out.  I hope this helps.