Brush shows grayed out until paint stroke

[Sue21872667s5vo]

New Brush

I have found the brush icon under masking and have been using but it has stopped working. It is now greyed out with a disabled type symbol as per pic below. Can you please tell me how to get it to work. I have signed out, turned my computer off and it is still not working. It is driving my crazy. Would love help from any clever person out there.

Thanks

[johnrellis]

Have you tried it on several different photos, raw and non-raw?  Unless someone knows exactly what this is, it will help to narrow down the proximate causes...

[Rob_Cullen]

You need to 'Paint' (Brush or apply a Gradient) on the image- first! for the ! icon to disappear.

    > Apply Brush >      

[johnrellis]

Thanks Rob, I never noticed that and just assumed it was unusual!