Magnetic Field Simulation

Hi,

i'm currently trying to do a mf analysis of the system in append figure.
The four quadrangular structures are coils with a external current applied. I defined all the domain's material and added the multiturn coil domain system for each coil.
But every time the result is :
Cannot Evaluate Expression

Failed to evaluate variable.
-Variable : T
Geometry : 1
Boundary : 19 -36 (last coil) or 19-90 (all coils)
-Expression :T
-Plot: surf 1

Any ideia of what i'm doing wrong?

Thank you