Issue getting uploader to recognize PDF's

[eluser]Unknown[/eluser]
Hey Guys,

So I have an uploader. and it uploads pictures just fine, I added PDF to it so I could upload PDF documents as well. however whenever I go to upload a PDF it won't work.

any ideas?

[eluser]noideawhattotypehere[/eluser]
My idea is that you should not expect any help without posting your code.