Having trouble dual booting fedora and windows.

Hi all,

I am having trouble installing Fedora 17 on my laptop which has windows already.
I make a partition of about 80 gigabytes in the fedora installer and it shows up as free space, however when I click to install on free space, it gives me an error saying there is not enough space. I have tried going the custom way and it still gives me the same error. Please let me know if you need any additional information.
Please help me I need it for science fair