If a defendant commits a second offense while on parole for a first offense, the timing of the parole revocation is key. If parole has already been revoked at the time of sentencing, as in Ex parte Wrigley, the trial court may stack the second sentence on top of the original sentence. However, if, as in this case, parole for the first offense has not yet been revoked, a cumulation order from the trial court is invalid because a defendant in that scenario has “made parole” and his sentence has “ceased to operate” under Code of Criminal Procedure Art. 42.08. Read.