Is a UK top case compatible with a US MacBook?

I needed to replace the top case on my (US) unibody macbook but since I'm in now living in the UK, it was easier to get a UK top case as in here:

http://www.amazon.co.uk/exec/obidos/ASIN...

The repair went smoothly, all the new connectors fit into the logic board the same way the old top case did. My computer started up fine and I had all my files and programs but the keyboard and trackpad are acting up.

A few keys work, most keys don't work at all, and some keys do things they aren't supposed to (backspace is volume-up, space is "=", etc). Also, the trackpad thinks that a single tap is a double tap.

I made sure that the connections were secure and tried changing my Language & Text format and input settings to UK, but nothing has worked. Are these top cases incompatible or do I have a faulty part?

Update: I plugged in a USB mouse because the single-tap-is-double-tap was keeping me from doing anything. Even with the mouse, the computer is interpreting a left click as a right click. This is very strange.