You can't move the color slider up because there is a file texture assigned to it . . . Click on the arrow pointing into the box and it should take you to the screen where it shouws the file texture.
If you do not want the texture there, right click the word color and break the connection . . .
"The Sage as an Astronomer: If you still see the stars as something above you, you lack the eye of knowledge." Friedrich Nietzsche