Liquid do they ever restrict which stocks you can

Liquid do they ever restrict which stocks you can buy? I have Scottrade and I had a big problem scooping up some MJNA a couple of weeks ago. I had to call in to place the trade. They guy told me they ordinarily charge an additional fee for placing the trade over the phone but he would make an exception. Despite my asking why the stock was restricted online he couldn't give me an answer. Plus their fees on some stocks are much more than the $7 they advertise.