Welcome to tex.sx. This is a documented feature of the AMS alignments. You need to use the environment form (which is anyway a good idea for all environments)
– David CarlisleMay 09 '13 at 17:00
3
Have a look at http://tex.stackexchange.com/questions/112558/some-newcommand-instructions-not-working
– Nicola TalbotMay 09 '13 at 17:00
Actually it is \beq that works incorrectly, it reads past the end of the paragraph: \eeq isn't executed at all.
– David CarlisleMay 09 '13 at 17:01
\beqthat works incorrectly, it reads past the end of the paragraph:\eeqisn't executed at all. – David Carlisle May 09 '13 at 17:01