You can keep trying but I wouldn't wait a whole week to try again. Maybe 3-4 days but a bp that size should be eating every 5 days. You seem to be doing everything right, just some bps take a while and others like mine just won't do it. But they say its easier to convert while they are young so I wouldn't give up just yet. Just keep an eye on the weight and make sure he doesn't start losing it. Otherwise you may need to go with live for a few feeds and try again later due to weight loss in a young snake not being the best thing to have happen.