Compressor giving out low quality H.264 videos

So I'm making screen videos using ScreenFlow and editing them through Final Cut Pro 7.
I'm having Screenflow capture my screen at Lossless settings, and then exporting them out to ProRes 422 HQ.
Now I dunno if this would be a tried-&-tested, thus recommended, way of doing things but this is what I'm doing...
Final Cut takes the videos in, no problem, and edits it fine, no problem.
Now that I send it to Compressor, trouble starts.
No matter how high I set the H.264 compression settings, the eventual output is pretty low quality at only 1500kbps.
The source video is close to 2,010,000bps.
Now I tried setting the H.264 compression to High and Best (multi-pass) and I also tried to 'restrict' the data rate and manually set it to 10mbps.
No matter what I do, the resulting video is always close to 1500kbps.
Handbrake follows the presets set by me to precise detail, but any video encoded through ProRes can't be recognized by it.
QuickTime conversion is my only other option, but it's exactly the same story there.
For more detail, I tried making a MPEG-4 movie, (H.264 baseline profile-10mbps-mulit-pass) and it's still no different.
What is going on? Any ideas?
Ronnie