Error while using mphinterp function

Dear All,

please help me regarding mphinterp function.....

while using,

coordinate=[29970,10080]'
'' electric_field=mphinterp(model,'(es.Ey*es.ny)','coord',coordinate)''
in comsol 5.0 with matlab, i am always encountered with the error message

Error using mphinterp
mphinterp : Java exception occurred:
Exception:
com.comsol.util.exceptions.FlException: Failed to evaluate
expression
(rethrown as com.comsol.util.exceptions.FlException)
(rethrown as com.comsol.util.exceptions.FlException)
Messages:
Failed to evaluate expression

Failed to evaluate expression

Cannot evaluate expression.

Undefined variable.
- Variable: comp1.es.ny
- Geometry: geom1
- Domain: 2

Failed to evaluate expression.
- Expression: real((comp1.es.Ey*comp1.es.ny))

Failed to evaluate expression.
- Expression: real(comp1.es.Ey*comp1.es.ny)

Error in Plea_Linepractice60micW_1micro_final29_2dModel (line
239)
electric_field=mphinterp(model,'(es.Ey*es.ny)','coord',coordinate)