Problem with CSSLess and IE CSS Filter

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CSS

Visual-Studio

IE9

VS2012

LESS

Hi,

I have the following less definition

.gradient(@from, @to) {
    background-color: @from;
    filter: ~"progid:DXImageTransform.Microsoft.gradient(startColorstr='@{from}',endColorstr='@{to}')";
    background-image: -webkit-gradient(linear, 0% 0%, 0% 100%, from(@from), to(@to));
    background-image: -webkit-linear-gradient(top, @from, @to);
    background-image: -moz-linear-gradient(top, @from, @to);
    background-image: -ms-linear-gradient(top, @from, @to);
    background-image: -o-linear-gradient(top, @from, @to);
}

I'm including it in the following style:

div.contentContainerForm {
    position: absolute;
    top: 80px;
    bottom: 15px;
    width: 100%;
    overflow: hidden;
    .gradient(#f0f0f0, #e0e0e0);
}

But I'm getting the following output when the css is generated:

div.contentContainerForm {
  position: absolute;
  top: 80px;
  bottom: 15px;
  width: 100%;
  overflow: hidden;
  background-color: #f0f0f0;
  filter: progid:DXImageTransform.Microsoft.gradient(startColorstr='@from', endColorstr='@to');
  background-image: -webkit-gradient(linear, 0% 0%, 0% 100%, from(#f0f0f0), to(#e0e0e0));
  background-image: -webkit-linear-gradient(top, #f0f0f0, #e0e0e0);
  background-image: -moz-linear-gradient(top, #f0f0f0, #e0e0e0);
  background-image: -ms-linear-gradient(top, #f0f0f0, #e0e0e0);
  background-image: -o-linear-gradient(top, #f0f0f0, #e0e0e0);
}

The problem is the failure to output the @from and @to variables for the filter property.

Any thoughts?