C.T.
Hi K.,
I hate to ask but have you tried to brid him ewith stickers or something he likes? I've heard about putting cheerios for target practice. Something to change the water? What's the difference between the potty's? Are you able to find out from daycare teacher what she did? I left my child naked a lot or put big kid panties on them instead of pull ups. If he did it in school and he isn't doing it now, does he not care or is it a regression? Hope I could help.
Best of Luck
Cassandra