i applied to two universities for phd ....i took 1 reco from MSEE usa prof and other from a colleague in my recent company in usa and one from a president of my previous company in usa.
is it true that recommendations should be from professors. i dont know if my BE profs are still ter at the university and other MSEE profs wer too busy.

is it ok to take recos from employers? or i have made a mistake.

kindly let me know. i am worried