I am currently in grad school, I was pregnant and I tried to get a visa for my grandma, (Sept 06), she was denied, of curse. I waited for 6 months and figured i would try again. So I have been checking the website since March this year and all I see is "Dates fully booked" and "date not available". I still check approx once per week.
I read somewhere that if you say the relative is coming to babysit, you are highly unlikely to be approved. How true this is, I do not know.
The rate of denials is closer to 99%, I think.
I'll post as soon as I am able to fix a visa appt. Please do the same and good luck.