Mysterious Line In the Clouds

[darthvader]

Here is a screen grab on a project I'm working on. For some reason whenever I insert a cirrus layes I always get the same 'line" where the clouds disappear along the horizon. Is this some sort of bug or am I just missing something?

[attachthumb=#]

[darthvader]

Never mind, I figure out what the problem was, mabye I should mess around on my own before asking silly questions.