Not compatible with Slick?

Hi, 

I'm giving a try to your json-annotation in an existing play-slick project.
When I add the @json annotation I'm having the following error in my sclik table definition : 

[error] value tupled is not a member of object models.Cpaid
[error]   def \* = (cpaid , custid )<>(Cpaid.tupled, Cpaid.unapply _)

Do I miss something?
