Problem with After Effects, Compositions.

Hi guys!,

I have a bit of a problem, I was busy with a project and busy with making comps as a placeholder and adding them in, in the main comp but I don't know how it happend but suddenly when I add in the placeholders in the main comp, they are invisible just as if I'd set the opacity to 0% but that is strange because there is a red solid in the placeholder comp.

Can someone help me out please??

Thanks!