Sorry to hear that you are experiencing problems. Check out a previous response from a different thread above. If that does not work let me know.
My other suggestion would be to close and re-open SketchUp and your file. Is your wall flat? Sometimes the dimension can be “eaten” by the wall (see below screen shot example) if moved after dimensioning or even if dimensioned incorrectly. Perhaps also you could attach your SketchUp file so we can take a look?
Cheers!
AlexB