How are you trying to use it? To use it you need to take the hash tag at the end of the skill calculator's URL to display the same build on the forum.
So let's say (randomly built spec)
http://www.torhead.com/skill-calc#300bcRRRdcdkqZrcoM.1 to use it on the forums I'd take everything after the # and put it in the middle of the BBCode tags.
PHP Code:
[skillcalc]300bcRRRdcdkqZrcoM.1[/skillcalc]
And that will become
http://f.cl.ly/items/3m0I3h2V2h3X3A0...00.56%20PM.png