The persistent level have lost a streaming level in the level window

I open a project few days ago and the persistent level have lost a level in the window level and now i can’t acces the level and it seam that the level i’m looking for is not in the open level tab. But the level is still in the right maps folder if i browse in the window explorer. If you look the screenshot the level is gray out and there a blue dot beside. What does this mean ?