Was it categorized right? I think there is a category for screenshots. But I'd read over the dA copyright rules for this.

As for the collabs, I've posted such as well and they've been no problem for me or the person I made them with.

A collab is a collaboration between two artists, meaning they both worked on the piece.

A render is when you colour over a screenshot or someone else's drawing.

As far as I know, as long as you clearly state the copyrights, they're allowed on dA.

Example of clearly stated copyright for a collab :

Art was made by Natticat8 and [insertnamehere].

Sketch was done by [insertnamehere]
Colouring was done by Natticat8

**As you can see, it's very clear in this example that TWO artists contributed to it, thereofore, there should be no problems as long as the other artist is ok with you posting it.

Example for clearly stated copyrights for a render :

Image, characters(c)[insertnamehere]
Colouring/rendering(c)Natticat8