Tom, try selecting "Clean" from the "Project" menu... the markup in your post looks syntactically correct, which causes me to suspect there's a minor corruption issue in your template design. A project clean typically clears out such corruption, allowing the build to complete successfully. Also, I'd recommend disabling "build automatically" (if you haven't already); do a manual build whenever you've made changes that you want to test, instead of allowing Designer to perform a full build every time.

 

On a side note, our names are eerily similar. Just a coincidence? 

Thanks for advice. Cleaning seemed to helped for simple cases like the one I described above but the problem reappeared after I started doing something more complex.
This time I got some kind of popup box during build telling me something important but I don't know what because the popup only had "ok"-button.

 

 

The username was accident; I had been searching the forum for a while before registering, alliterations get easily stuck in subconscious. I'll re-register so there will be no "evil twin" ;)

Update to my situation: cleaning helped in some cases but I eventually I had to go as far as deleting workspace in order to make successful build. Sometimes "internal error"-targets files I have not touched. Also, I usually get as many "document is not locked by you" messages during building than I get "internal errors" after it.

 

 At this moment I can only work on my own replica where I have disabled design lock.