I burned a video to a black DVD but it wouldnt play?

I Made a goodbye graduation DVD for my BFFL with Windows Live Movie Maker and when i was finished, I pressed the burn on and it saved then,burned onto the blank DVD. The type of Blank DVD it was, was a Fugifilm 4.7gb. I tried playing it on my TV because i wanted it to play on her TV on her grad party but, when i entered it, it sayd that ther was no disc inside... i put in in my computer again to see if it sud play on there and it sayd that the DVD was still blank after i already burned it... plese tell me what went wrong and what i have to do in order to burn this correctly! thnx :)