Without proper info on your system and documents nobody can know. Check your document color mode and the Channels palette as a start.
I have CC and my image mode was converted from Grayscale to RGB Color. I have been using quick mask mode to select the areas that I want colored on the figure that I am working on. Channel is set to 8 bits. Everything was working fine and then I went to create my next quick mask and it said that it was not available.
Please let me know if you need more information.
Thank you for being willing to help.
Okay I got the quick mask mode to work. However now when I create the mask the back ground and foreground color are incorrect in the chanel pallette. Even after ensuring the colors are correct before creating and saving the mask
For product specific questions you may do better in the specific product forum
If you start at the Forums Index http://forums.adobe.com/index.jspa
You will be able to select a forum for Photoshop
Click the "down arrow" symbol on the right to open the drop down list and scroll