Strange problems with Jammit

Question

Hi,

i use Jammit to pack all the .css and .js files in my project

I faced a strange problem, that really confused me...

When Jammit deals with .css, it kills some css rules.

The rules:

background-image: -webkit-gradient( linear, left bottom, left top, color-stop(0, #111111), color-stop(1, #303030) );

background-image: -moz-linear-gradient( center bottom, #111111 0%, #303030 100% );

Will be in packed version reduced to following:

background-image:0;

Maybe, i do something wrong ? (i doubt, though)