While i am trying to simulate my custom process i am getting this error "Object of type Person does not exist in database or you do not have the relevant viewing permissions."

This is a runtime error, not a compilation one

Seems you are using a where clause somewhere in your process which is not returning a value and you are probably trying to create an IEntity based on that

Thanks for the response,

Yeah i am using where clause in my process steps like below

Dim f As ISqlFormatter = Session.SqlFormatter
Dim whereclause As String
whereclause = f.AndRelation( _
f.Comparison("XYZ",$XYZ$,ValType.String,CompareOperator.Equal), _
f.Comparison("ABC",$LMN$,ValType.String,CompareOperator.Like))
value=whereclause