less2css won't compile dynamically created class names - less

Question

I'm using a sublime text 2 plugin less2css to compile my less files into css files. The issue I'm having is that the plugin won't compile my mixin which is used to dynamically create header font size. I've tested the mixin with the online less compiler which winless offers, and it seems to work fine.
Is this just a bug with the plugin, or am I doing something completely wrong in my mixin?
Mixin:
#fontSize: 24px;
.calcFontSize(#index) when (#index > 0) {
(~'h#{index}') {
font-size: #fontSize - #index * 3;
}
.calcFontSize(#index - 1);
}
.calcFontSize(0) {}
.calcFontSize(6);
The issue seems to occur on this line: (~'h#{index}') {. Changing this to an h1 (or any other header element) works fine.

Answer 1

Your code (and WINLESS too, I believe, which is why it works there) is using older syntax for LESS CSS. Your code compiles fine at http://less2css.org/ when set to LESS 1.3.0-1.3.3, but there was a syntax change for LESS 1.4+ (no interpolation needed). So if your Sublime has upgraded the LESS to 1.4+, then that would explain why your code does not work.
If this is in fact the issue, then you just need to change the syntax of your line like so:
h#{index} {
font-size: #fontSize - #index * 3;
}
Which you can see works on http://less2css.org/ for the 1.4+ versions of LESS.