If you presented yourself as having a background with TD, then you deserve what you get...that is, more than likely, not hired.
Now, on the other hand, if TD is something you'll be interacting with in this position and you haven't stated that you have any sort of background with it, you would be better served by saying that you haven't used the software.
Going one step further, if you have used some form of bug tracking software previously, making the leap to TD is not much of a leap.
Bottom line: Be honest about your knowledge, skills, and abilities. The interviewer will be able to detect lies or a misrepresented background.
"The single biggest problem in communication is the illusion that it has taken place."
-George Bernard Shaw, Irish playwright and Nobel Prize winner, 1856-1950