Why I get -1 from stored procedure?

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SQL-Server

.NET4.5

, +

I use SQL Server 2012 and Entity Framework6.

I created table valued parameter:

CREATE TYPE IdArray AS TABLE 
    (
         Id int
    );

And here my stored procedure:

ALTER PROCEDURE [dbo].[SP_TEST_TLP]
        @List dbo.IdArray READONLY 
    AS 
    BEGIN
        SET NOCOUNT ON;
    
        SELECT * 
        FROM Clients 
        WHERE Clients.Id IN ( '@List' )
    END

From Visual Studio I call stored procedure and passing paramaters to stored procedure.

I do it this way:

Create DataTable:

var myDataTable = new DataTable();
     myDataTable.Columns.Add("Id", typeof(int));

     myDataTable.Rows.Add(1);
     myDataTable.Rows.Add(3);
     myDataTable.Rows.Add(6);

Creating `SqlParameter` from DataTable:

SqlParameter parameter = new SqlParameter();
     parameter.ParameterName = "@List";
     parameter.SqlDbType = System.Data.SqlDbType.Structured;
     parameter.TypeName = "dbo.IdArray";
     parameter.Value = myDataTable;

Fire stored procedure and passing parameter:

var data = _context.Database.ExecuteSqlCommand("SP_TEST_TLP @List", parameter);

The problem is that `ExecuteSqlCommand` returns -1.

Why `ExecuteSqlCommand` returns -1 while I expect rows from database?

What I have tried:

I tryed the above but it didn't work!