I can't seem to move my artifacts from one museum to another.

[LoneDragon]

So I can't get theme bonuses. What am I doing wrong?

 

[zyx]

To move artifacts the museums involved must not have any free slots, if I remember correctly. So you need three artifacts - six for British museums - each.
Do you have a mod installed? This could mess up your mouse functions.

 

[LoneDragon]

I see...I was reading the UI as only the sending museum had to be full.