Cell Background color change

hi,
in my excel project , when iīm trying to change the background color of the cell its not possible and the result is the background color is still the same .. i know , itīs detail , anyway ..

any idea whatīs wrong with these cells ? ( i do not work only in some cells in the worksheet )

thanks

Check the cell does not have conditional formatting applied to it.

then you need to show us the code you are using.

Post and example workbook if possible