ConnectionStrings not working when I publish solution

When I publish my project I get this error:

System.Data.SqlClient.SqlException (0x80131904): Login failed for user 'serverusername'. at System.Data.SqlClient.SqlInternalConnectionTds..ctor(DbConnectionPoolIdentity identity, SqlConnectionString

The reason why Im getting the error is cause I'm using windowns authentication for that connectionString. It works well in my local machine but when I publish different server that has that site it gives me that error. It should be using windowns authentication because this is not the first app I have publish on that server, so I dont understand why when it connects to that server 'thisserver' it doesn't connect with the correct windowns authentication.

 <add name="wfserver" 
      connectionString="Server=thisserver;Database=thisdatabase;Integrated Security=True;MultipleActiveResultSets=True;Trusted_Connection=True;" 
      providerName="System.Data.SqlClient" /> 

//     using (SqlConnection conn = new SqlConnection(connectionString))
using (SqlConnection conn = new SqlConnection(ConfigurationManager.ConnectionStrings["wfserver"].ToString()))
{

   "select * from mytable where year = @yearnumber ";

    SqlDataAdapter sda = new SqlDataAdapter(query, conn);
    sda.SelectCommand.Parameters.AddWithValue("@yearnumber", year);


    DataTable dt = new DataTable();
    sda.Fill(dt);
    List<workflowMonthly> modelList = new List<workflowMonthly>();
    foreach (DataRow row in dt.Rows)
    {
        var model = new workflowMonthly()
        {
            WorkflowName = row["WorkflowName"].ToString(),
            ...
        };

        modelList.Add(model);
    }

    return modelList;
}

I have a form and the issue happens after I click submit and looks for the data

View:

  @User.Identity.Name (shows correct windows authentication)

  @using (Html.BeginForm("page", "Reports", FormMethod.Post, new { id = "commentForm", role = "form" }))

 {}

Are you publishing the site local? If so then what ever you are using to access SQL Server from SSMS you should not be have a problem. If you are publishing to another location then I would create a dbname and password and replace you Webconfig CnnectionString.

In shorts create a sa like account and password. Try something like this. "Server=myServerAddress;Database=myDataBase;User Id=myUsername; Password=myPassword;"