lighting

Hello everyone, I just recently began mapping and so far it's been going pretty well, however I wanted to create a texture that acts as a light source, which after a quick google search I found an article in the developer wiki and various youtube tutorials showing how it is can be done via...

I'm not exactly sure when they started occurring or why but after one test compile I noticed that there were some fairly ugly shadows on the wall that were not there before. This is what they look like: The issue does not appear to happen in any of the other rooms besides the one above...