Cannot adjust brightness/contrast of layer

[rdh61]

Hi,

I am designing a book cover. I have one layer for the image for the front cover, another for the back cover. I can easily adjust the brightness/contrast of the front cover image, but I cannot for the back cover image. Here's what I am doing:
1. Open dockable dialogue: Layers.
2. Select the layer I want to work on.
3. Select Colours -> Brightness-Contrast.
4. Adjust as desired.
5. Click OK.
With the front cover, the brightness/contrast change is immediate. With the back cover, nothing happens. I am using GIMP 2.8.10 on Lubuntu and Linux Mint (2 computers).

Thank you for your help.

[Ofnuts]

Maybe you have a selection that only encompasses the first layer(*). Id Select>None is not grayed out, you have a selection, so just remove it.

(*) To be altered, a pixel has to be 1) in the active layer and 2) covered by the selection mask, if there is one.

[rdh61]

(03-06-2019, 08:30 AM)Ofnuts Wrote: Maybe you have a selection that only encompasses the first layer(*). Id Select>None is not grayed out, you have a selection, so just remove it.

(*) To be altered, a pixel has to be 1) in the active layer and 2) covered by the selection mask, if there is one.

Thank you for your reply. I'm not sure if my solution corresponds to your first answer, but you did point me in the right direction, and I now understand the principal explained after your asterisk. 'Select>None' WAS grayed out, but I clicked 'Select>All'. When I did that, "Select>None" was no longer grayed out (logically), and now I can adjust the brightness/contrast of both layers.