Specified Cast Is Not Valid

Can't seem to find why I'm getting this error: Specified cast is not valid.

Ok, using a stored procedure for SQL Server 2000 and here is the main part of it:

 SELECT id, rank, firstName, lastName, service, status, createdTime
 FROM   accessRequest
 WHERE  lastName LIKE @tLastName
     AND    firstName LIKE @tFirstName

And the C# code behind from the class file:

SqlDataReader spResults;

conn.Open();

spResults = command.ExecuteReader();

while( spResults.Read() )

{

AccessRequestSearch request = new AccessRequestSearch( (int)spResults.GetInt32( 0 ), spResults.GetString( 2 ), spResults.GetString( 3 ), spResults.GetString( 1 ), spResults.GetString( 4 ), spResults.GetString( 5 ), Convert.ToDateTime(spResults.GetString( 6 )));

searchResults.Add( request ); // Add to Array List

}

spResults.Close();

The part in red is where I think it's happening because that is what I just added to the request.  createdTime in the table is set as DateTime.

Can anyone see what I am missing here?

More info is available if needed.

Thanks,

Zath