Believe me persistance is the key. DOn't stop putting him in it otherwise it may be hard later. I would try putting him in the pram inside your house when he is normally in the bouncer or on the floor(not all the time maybe once a day for a few days). He might find it more comfortable being in a familiar environment and he may get used to it. I also found wriggling the pram a little when stopped worked.HTH
Nikki