Gui alpha change

I want to make the label gradually faded:

 var originalColor = GUI.color;            
 if( _needChangeLanguageVisibleText ) {
                 _alphaLanguage -= 2;
                 _languageImageAlphaCoef = _alphaLanguage/255.0f;
                 GUI.color = new Color( originalColor.r, originalColor.g, originalColor.b, _languageImageAlphaCoef );
                 GUI.Label(
                     _drawLanguageTextRect,
                     "",
                     _guiTextStyle
                          );
                 GUI.color = originalColor;
         }

It works in the Unity and in the web player, but when I build a standalone player for windows, it does not work. Moreover, if before drawing GUI.Label (... write Debug.Log (message), then everything works fine in the standalone player. How to solve the problem without Debug.Log()?