Why won't my iPhone let me upload videos to YouTube?

I've tried every way, none seem to work.
I've made a video using the app: Video Star (iPhone market), and now when I try to upload my video to YouTube, it always shows an error message saying something along the lines of 'not connected to YouTube account'. I can sign in to my YouTube account, but if this is the case, what could I do?

It wont not uploaded from the i phone