Is the Mask applied to an Adjustment Layer above the Layer that is Source Footage (the concentric rings)?
If so, cut and paste it from the Adjustment Layer to the rings layer. If the Spacial Resolution of the two layers does not match (that is, they are not the same width and height), you may have to nudge the Mask after pasting it.
Hi Warren, those concentric rings are a radio wave effect. I have applied the mask to the adjustment layer (It's not working). If I try to apply the mask to the solid layer with the radio waves effect it becomes a shape.