Does your probation officer know that you have been attending ADS? If not, make sure he or she knows immediately, and offer to show documentation. Were you attending before your summons was served? If you are in compliance with the terms of your probation, it is unlikely you will be be revoked. You certainly have the option to present your evidence of compliance at your hearing. It would be a good idea to hire a lawyer in this situation to represent you at your hearing.
The chances of your probation being revoked and your suspended sentence being imposed depends on the information the Judge receives about your particular situation.
An attorney can help you review the circumstances that led your Probation Officer to request a probation violation hearing. For example, the attorney can review the court's case file to determine the terms of your probation and what term was allegedly violated that triggered the probation violation.
An attorney can also help you gather information and documents to support your position that you are not in violation of the terms of your probation. An attorney can then speak with your Probation Officer before the hearing to inform him of your performance of your probation terms, with the goal of convincing him that there is no violation or to agree to something that will not hurt you.
An attorney can represent you in Court, speaking with the Prosecutor and the PO (again), with the goal of resolving the hearing in a favorable way, and eventually speaking with the Judge.
I suggest that you consult an attorney about your situation at your earliest opportunity.