Hi,
Today i had an interesting problem, i would like to share just in case some of u get into similar situation. All day i had WLP streaming few symbols that i was trading intra-day. I was using ATP to place order and it SEEMED to work fine I made a few trades, the next buy opportunity came along and tried placing order through ATP. It did not let make the trade saying i was out of my intra-day margin and that a had a Fed-call. I was pretty sure that i did not exceed my buying power and could not be in Fed-call. Mean while i am talking to fidelity rep on the phone, and he did confirm that I had neither any FED-call nor had i exceeded my intra-day buying power (which i knew anyways). Then the ATP web support got on the line, he looked at my ATP accounts and he said that I did have margin-call and exceeded intra-day limit.
Ultimately, the problem got resoved was Restarting the ATP. The Web support told me that some times ATP gets out of sync with fidelity.com server and hence the problem. Mean while i missed an opportunity to make a few bucks.
So, keep restarting ur ATP few times a day..so it correctly syncs up with fidelity.com.