dallas

I was super excited last Friday because I booked a flight to dallas for a weekend to attend the parker seminars in September. I got a good price on a flight and was very excited to go. Well I told my boss that I was planning on attending and she said no. she said I cant be gone from the office because we are not busy enough for me to miss. (this was in a note on my desk, she couldnt speak to me in person). So I called and left a message that I wanted to talk about it and she would not return my phone call. So today I called her husband and the receptionist screened my call and 2 hours later the wife called me back. she was basically telling me I could not go.
My argument is
1 this is not paid time off
2 hire a fill in (which I have to pay for)
3 at this point i will have been there 6 1/2 months and i am entitled to 1 day off which is for a seminar
she still says no. then i say i have booked the flight already. after finding like 10 ways to put me down on the phone she says she will talk to her husband and let me know on monday.
seriously i dont think I am asking for much but obviously i am.
If she tells me no, I may not be able to stick this crap out much longer. at all!