You are going to have to give him more time to get used to having the playstand around, I had the same issue with Josey when I introduced a new playstand. Greys are very cautious creatures and scared of new or different things, put the playstand where he can see it and then start bringing it closer one day, then the next day bring it a little closer and so on until he is comnfortable with it being close then try putting him on it. Maybe put a toy or two on it to entice him to want to get on it, you play with the toys on it and that might make him interested enough to want to investigate it and then you have it made.