Sketch filters not working

I have recently been able to apply the Sketch filters to a jpg file. For some reason, when I apply any Sketch filter now (even to the same file I was able to manipulate with the sketch filter previously), the image becomes all white. When I apply any of the other filters to the same image (Stylize, Texture, etc...) the filter works.

Have I accidentally changed a setting somewhere?

Thanks,
Angela

I figured it out, thanks to the Adobe PS CS Bible.....both my foreground and background colors were set to white! I changed my foreground color to black and now it works as expected.