American Association of Foreign Educated Nurses

I received a letter from the National Visa Center asking me to pay my Visa fee sometime in August 2007. I sent the payment via Dollar draft but up until now I have not received my Ds230 form. I wrote them thru email asking why is this so. They just said there were still no visas available but no confirmation whatsoever whether they got my payment or not. Does it really happens or mine is an isolated case? Hope to get your thoughts on this. Tnx