Getting error could not find an implementation of the query pattern

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MVC4

entity-framework

I have "Datatbase1.tt" file as i press "ctrl+s"(save) then i get this error

"Could not find an implementation of the query pattern for source type 'int'. 'Select' not found " on "bold font text" below

using (var context = new JobTrackDbContext())
{
retval = (from ai in context.JtContrAssignmentInfo(AssignmentId)
select new JobTrackAssignmentDetailsViewData
{
InsuredName = ai.InsuredName == null ? "" : ai.InsuredName,
InsuredEmail = ai.InsuredEmail == null ? "" : ai.InsuredEmail,
InsuredPhone = ai.Phone == null ? "" : ai.Phone,
LossAddress = ai.LossAddress == null ? "" : ai.LossAddress,
ClientName = ai.ClientName == null ? "" : ai.ClientName,
Claim = ai.Claim == null ? "" : ai.Claim
}).First();
}

What I have tried:

I have added following namespaces

using System;
using System.Collections.Generic;
using System.Linq;
using System.Collections;
using System.Data.SqlTypes;
using System.Text;
using System.Threading.Tasks;