command line lessc reports random syntax errors

We are experiencing a bizarre random behavior of the LESS compiler at the Windows Command Line. We are getting inconsistent syntax error messages like we were missing variables or mixins declarations. The thing is, if we LESS compile the same file a second time, the compiler works just fine and we get our beautiful CSS file. The same files work just fine using the client side less.js while running our solution in Visual Studio.

Some more details: LESS compiler (less@1.4.0-b4) at the Windows7 Command Line. Here is what I type on command line: lessc --include-path="site/Css" Css\results-imports.less > fileoutput.comb.css --yui-compress results-imports.less has a list of less files that should be imported and compiled into css files, some of the less files have nested imports as well.

we get errors like: NameError: variable @brand-color-14 is undefined in C:\Css\loadmask.less. This is one of the imported less files @brand-color-14 is declared in one of the less files that should have been imported before loadmask.less