Change metric name to an invalid name so that exception is raised

I just found your ROmniture library and was planning on using it for my project, so I started off by running the tests you provided with it.  One of the tests was failing because I was not getting an exception when commerce and traffic variables were mixed.  It seems that Omniture now allows this.

So, I modified the test to have some other behavior that would cause an exception - in this case, I just but in a bad element name.  This causes the exception to be properly raised and thus the test to properly fail.