I have had a jailbroken Iphone4 for awhile now (5.1.1), and yesterday when I was installing something from cydia (resupported4) It froze and I panicked and held down the Power and Home buttons to restart it. After I did that, it would show the Apple Icon, but would never make it past that. At this point I just wanted to get it working again, so I put it in recovery mode and restored it. It took awhile and but eventually it was restored to 6.0.1.

After I had it working and had most of my files back, I started looking for how to downgrade. After a long search I found what I thought I needed and went to work. I downloaded TinyUnbrella and found my shsh files, I downloaded the right firmware for my iphone (6.0 and 5.1.1, the tutorials I I found said I needed to downgrade to 6.0 and then 5.1.1) And I updated redsn0w and then snitched a personal 6.0 and 5.1.1 ipsw file.

Now all I had to do was select the custom file to restore with, but when I tried to(I had put my iphone in recovery mode/dfu mode) all that came up was a popup that said "The Iphone "Iphone" could not be restored. This device isn't eligible for the requested build." I searched for fixes for this, but it seemed that nobody was having this problem. For what did come up, It was problems with ios 4, and having to modify my host files. When I looked into that, my host files did not look like their's.

If any of you has had this happen, or know how to fix it, please help me.
Thank you in advance.

Tl;dr Version
I am trying to downgrade from ios 6.0.1 to 5.1.1. But when I try to restore using a custom ipsw file, all that happens is that it extracts the software getting ready to restore, and then the popup "The Iphone "Iphone" could not be restored. This device isn't eligible for the requested build." Appears. What should I do to fix this?