Why can't you use the toy? It should be what is rewarding to the dog....if that's it? It would be like you could pay me in dark chocolate and I'd be meh, but if you brought out the milk chocolate, my engagement would increase.
Relationship Centered Training | Suzanne Clothier
is a nice article about the relationship, which is the foundation.
But I am not sure the exact deal here of what she is saying to you.