Big problem!

DG today and I was the only one trying to use the 'Vanishing point filter in Photoshop cc.  Not easy but I got to the stage of having imported the girls paintings and then went to save as a jpg to load up here.  The canvases went black - bottom image.  To get the photos in I had to take a screen shot!

I was following this tutorial.

Could anyone help?  I had to give up!