If i have an Interlock devise, what are the penalties for failing a test?

The penalties vary from state to state and you should consult with an attorney in your area. If you fail the test a certain number of times (in some states it is 3) or fail any "rolling" tests that you are required to take once the vehicle is in motion to make sure that you continue to be sober to drive, device goes in to a "lock-out" mode and will basically shut you out.  You will be shut out and need to pay a fee to have it reset and to get a new code to get the vehicle moving again.  Generally, a violation in using the device is a violation of your probation, so all the bad stuff that goes along with violating those rules will go along here.  You could lose the right to drive entirely by suspending or revoking your license.  Could probation be revoked?  Possibly.  It is really best to seek legal help if this has happened.  Good luck.