Invalid RGB color string

[Pedro M.]

Hi i'm using Powershell and dotless.Compiler.exe version 1.3.1.0 to compile my less files.
I'm getting a error trying to compile a less with a variable using a background color and a image.

So I have the value
      @tuningBodyBg:#4180ab repeat-x left top scroll url(images/bg.pictures.0103.jpg);

and do this to get only the color
@tuningBodyBgString:"@{tuningBodyBg}";

But is I'm getting this error trying to use the function color:

Invalid RGB color string '4180ab repeat-x left top scroll url(images/bg.pictures.0103.jpg)' on line 5 in file 'tuning.less':
  [4]: @tuningBodyBgString:"@{tuningBodyBg}";
  [5]: @tuningBodyBgColor:color(@tuningBodyBgString);

Someone can tell me how to resolve this?