A couple of questions:
Has your ball previously eaten PK rats?
Has your ball eaten on a regular cycle?
Two suggestions if the previous answers are YES
*Remove the ball from all other distractions (possibly put it in a small box) - wiggle the rat in front of it's face (with tongs not fingers!)
*If that fails try placinig the rat and the ball in a brown paper bag overnight
If the first is NO:
*Just go with live prey
If the second is NO:
*I'm not sure... never had my balls go off-feed. Hopefully someone else can help you with that. I'd say try a live rat or maybe try again in a week?
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-Iman
1.1 Balls
0.1 Boa (BCI)
0.0 Experience
100.0 % LOVE
Hope it helps...