Was having fatigued pitching at the ML level and had to move a position player down and a pitcher up.  It was after the trade deadline so I designated a player for assignment with revokable  waivers my player was claimed and I recalled him.  When I tried to put him back in my ML roster and moved another guy to the minors I received an error and I had to trade or release him (it also said I could move him to the minors, but he was claimed so I could not do that).  Did I screw up and now have to trade or release him? 

if a guy with zero options is designated and then claimed on revocable waivers then, yes, you're stuck.  he must be traded or released.

That situation is one of the reasons some owners put all their 40-man guys on revokable waivers once the trade deadline hits. Most will clear, a couple will get claimed, but then you know who has the flexibility to be sent to the minors later in the season, and who has to stay with the MLB club.