Why this strange behavior of sqlbulkcopy in a asp.net website running under iis?

Question

I'm using SqlClient.SqlBulkCopy to try and bulk copy a csv file into a database. I am getting the following error after calling the ..WriteToServer method.

"The given value of type String from the data source cannot be converted to type decimal of the specified target column."

Here is my code,

 dt.Columns.Add("IsDeleted", typeof(byte));
    dt.Columns.Add(new DataColumn("CreatedDate", typeof(DateTime)));
    foreach (DataRow dr in dt.Rows)
    {
        if (dr["MobileNo2"] == "" && dr["DriverName2"] == "")
        {
            dr["MobileNo2"] = null;
            dr["DriverName2"] = "";
        }
        dr["IsDeleted"] = Convert.ToByte(0);
        dr["CreatedDate"] = Convert.ToDateTime(System.DateTime.Now.ToString());
    }
    string connectionString = System.Configuration.ConfigurationManager.
                          ConnectionStrings["connectionString"].ConnectionString;
    SqlBulkCopy sbc = new SqlBulkCopy(connectionString);
    sbc.DestinationTableName = "DailySchedule";
    sbc.ColumnMappings.Add("WirelessId", "WirelessId");
    sbc.ColumnMappings.Add("RegNo", "RegNo");
    sbc.ColumnMappings.Add("DriverName1", "DriverName1");
    sbc.ColumnMappings.Add("MobileNo1", "MobileNo1");
    sbc.ColumnMappings.Add("DriverName2", "DriverName2");
    sbc.ColumnMappings.Add("MobileNo2", "MobileNo2");
    sbc.ColumnMappings.Add("IsDeleted", "IsDeleted");
    sbc.ColumnMappings.Add("CreatedDate", "CreatedDate");
    sbc.WriteToServer(dt);
    sbc.Close();

There is no error when running under visual studio developement server but it gives me an error when running under iis.....

Here is my sql server table details,

[Id] [int] IDENTITY(1,1) NOT NULL,
[WirelessId] [int] NULL,
[RegNo] [nvarchar](50) NULL,
[DriverName1] [nvarchar](50) NULL,
[MobileNo1] [numeric](18, 0) NULL,
[DriverName2] [nvarchar](50) NULL,
[MobileNo2] [numeric](18, 0) NULL,
[IsDeleted] [tinyint] NULL,
[CreatedDate] [datetime] NULL,

Answer 1

Can you provide sample data?

Sounds like it's one of the mobile numbers. Id start with isolating the exact column then checking the source data. Also, it sounds like the DataTable is all string values, try typing the dataset.

Answer 2

If I had to guess - culture. What culture is IIS using, and what culture is your desktop app using? commas vs periods etc.