Can't help on the color, Tareq. But on the black are YOU sure? I mean, did you remove the slide completely form the film holder and either hold it in your hand (tapping nervously, perhaps) or place it somwhere until you tripped the shutter then reinsert it? Because I agree with K. That looks like a darkslide blocking light. The only other explanation I might come up with is that that portion of the film received NO development. But I find that rather unlikely.
Glad you like it and things look to be going well so far.