Eye dropper tool

[Tdtimd17]

Eye dropper window goes black sometimes. How can I prevent this?

[Mariam Hovhannesyan]

Please can you explain what do you mean by window goes black? Or do a screenshot of it

Thanks 

[Tdtimd17]

I mean the color preview circle window is all black. When I try to select a color from an image the preview window and the color settings go to black and I can't pick any colors. Please help me if you can.