Failed to convert parameter value from a SqlParameter to a String

[balajius]

I am using VS2008 with asp.net 3.5 and enterprise library 4.1. I am getting the following error when I try to connect to database.
"Failed to convert parameter value from a SqlParameter to a String"

Here is my code

Database db = DatabaseFactory.CreateDatabase("SQLSRVR");

string myStoredProcedure = "usp_GetPersonContact";
            
SqlParameter[] SQLParameters = new SqlParameter[1];
SQLParameters[0] = new SqlParameter("@ln", SqlDbType.NVarChar, 50);            
SQLParameters[0].Value = "Smith"; 
SQLParameters[0].Direction = ParameterDirection.Input;

DataSet resultDataSet = null;
resultDataSet = db.ExecuteDataSet(myStoredProcedure, SQLParameters);

I already tried conversion but seems nothing is working. Please let me know what i am doing wrong. Thanks.

[PandiarajanChellappan]

Chage the type SqlDbType.NVarC har to SqlDbType.VarCh ar..
then it will work.....
(ie) change ur code like this,,,,,

SQLParameters[0] = new SqlParameter("@ ln", SqlDbType.VarCh ar, 50,"ln");
..

[balajius]

Hi,
Chage the type SqlDbType.NVarC har to SqlDbType.VarCh ar..
then it will work.....
(ie) change ur code like this,,,,,

SQLParameters[0] = new SqlParameter("@ ln", SqlDbType.VarCh ar, 50,"ln");

Thanks,
Pandian...

Thanks for the help Pandian.

Still is not working. Here is the latest code
C#

Database db = DatabaseFactory.CreateDatabase("SQLSRVR");

string myStoredProcedure = "usp_GetPersonContact";

SqlParameter[] SQLParameters = new SqlParameter[1];

SQLParameters[0] = new SqlParameter("@lastname", SqlDbType.VarChar, 50, "LastName");            

SQLParameters[0].Value = "Smith"; 

SQLParameters[0].Direction = ParameterDirection.Input;

DataSet resultDataSet = null;

resultDataSet = db.ExecuteDataSet(myStoredProcedure, SQLParameters);

Storeprocedure

ALTER Procedure [dbo].[usp_GetPersonContact]@lastname varchar(50)   
as 
select * from Person.Contact where LastName = @lastname

[Frinavale]

I don't use C# on a regular basis so I held off answer before now.
Please review the following article that outline how to use a database. The first article has examples on how to provide parameters to a SqlCommand.

Database tutorial Part 1
Database tutorial Part 2

-Frinny