数据表值不匹配使用SqlGeography和c#

所以，下面的代码给了我一个相当令人困惑的异常。

public void BuildTable()
        {
            using (SqlConnection connection = new SqlConnection("Data Source=ylkx1ic1so.database.windows.net;Initial Catalog=hackathon;Persist Security Info=True;User ID=REDACTED;Password=REDACTED"))
            {
                SqlGeographyBuilder builder = createTestPoint();            
                SqlGeography myGeography = builder.ConstructedGeography;
                connection.Open();
                DataTable myTable = new DataTable();
                using (SqlDataAdapter adapter = new SqlDataAdapter("SELECT * FROM myTable", connection))
                {
                    SqlCommandBuilder cb = new SqlCommandBuilder(adapter);
                    adapter.Fill(myTable);
                    myTable.Rows.Add(6, "Test", myGeography);
                    adapter.Update(myTable);
                }
            }
        }
        private SqlGeographyBuilder createTestPoint()
        {
            SqlGeographyBuilder builder = new SqlGeographyBuilder();
            builder.SetSrid(4326);
            builder.BeginGeography(OpenGisGeographyType.Point);
            builder.BeginFigure(31, -85);
            builder.EndFigure();
            builder.EndGeography();
            return builder;
        }

行myTable.Rows。Add(6， "Test"， myGeography);是我得到以下异常的地方:

Type of value has a mismatch with column typeCouldn't store <POINT (-85 31)> in placemark Column.  Expected type is SqlGeography.

我不明白的是为什么这会失败。在调试时，我尝试了这个:

for (int i = 0; i < myTable.Columns.Count; i++)
                    {
                        Debug.WriteLine(myTable.Columns[i].DataType);
                    }
                    Debug.WriteLine(myGeography.GetType());

我的输出是:

System.Int32
System.String
Microsoft.SqlServer.Types.SqlGeography
Microsoft.SqlServer.Types.SqlGeography

因此，我显然试图将SqlGeography对象放在接受SqlGeography对象的列中

string sqlCommandText = "insert into myTable(col1,col2,col3) Values(@col1,@col2,@col3)";
SqlCommand sqlCommand = new SqlCommand(sqlCommandText, connection);
sqlCommand.Parameters.AddWithValue("@col1", 6);
sqlCommand.Parameters.AddWithValue("@col2", "Test");
sqlCommand.Parameters.Add(new SqlParameter("@col3", myGeography) { UdtTypeName = "Geography" });
sqlCommand.ExecuteNonQuery();