dielectric properties of ice

Hi,
I am modelling ice between two nonparallel capacitor plates to model its dielectric properties variation at different frequencies.
I am using sweeping the frequency in the stationary studies.
Unfortunately i m unable to resolve this problem,

Failed to evaluate variable.
- Variable: mat.epsilonr22
- Geometry: 1
- Domain: 7 8 9 10 28 30
Failed to evaluate variable.
- Variable: mod1.es.epsilonryy
- Defined as: mat.epsilonr22
Failed to evaluate variable.
- Variable: mod1.es.Dy
- Defined as: ((epsilon0_const*mod1.es.epsilonryy)*mod1.es.Ey)
Failed to evaluate expression.
- Expression: d(((-mod1.es.Dx*test(mod1.Vx)-mod1.es.Dy*test(mod1.Vy))*mod1.es.d)*(dvol),{test@1})

Please help me in resolving this!