Unable to edit gridview row

I was learning through General asp.net videos. I'm currently on Chapter 8 where Bob Tabor shows us how to make the grid view edittable. I did the same thing, I  clicked edit , made changes but the moment i clicked update link it gives an error

Incorrect syntax near 'nvarchar'.

  Exception Details: System.Data.SqlClient.SqlException: Incorrect syntax near 'nvarchar'.

Source Error:

An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.

Stack Trace:

[SqlException (0x80131904): Incorrect syntax near 'nvarchar'.] System.Data.SqlClient.SqlConnection.OnError(SqlException exception, Boolean breakConnection) +98 System.Data.SqlClient.SqlInternalConnection.OnError(SqlException exception, Boolean breakConnection) +82 System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning(TdsParserStateObject stateObj) +346 System.Data.SqlClient.TdsParser.Run(RunBehavior runBehavior, SqlCommand cmdHandler, SqlDataReader dataStream, BulkCopySimpleResultSet bulkCopyHandler, TdsParserStateObject stateObj) +3430 System.Data.SqlClient.SqlCommand.FinishExecuteReader(SqlDataReader ds, RunBehavior runBehavior, String resetOptionsString) +185 System.Data.SqlClient.SqlCommand.RunExecuteReaderTds(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, Boolean async) +1271 System.Data.SqlClient.SqlCommand.RunExecuteReader(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, String method, DbAsyncResult result) +334 System.Data.SqlClient.SqlCommand.InternalExecuteNonQuery(DbAsyncResult result, String methodName, Boolean sendToPipe) +407 System.Data.SqlClient.SqlCommand.ExecuteNonQuery() +149 System.Web.UI.WebControls.SqlDataSourceView.ExecuteDbCommand(DbCommand command, DataSourceOperation operation) +495 System.Web.UI.WebControls.SqlDataSourceView.ExecuteUpdate(IDictionary keys, IDictionary values, IDictionary oldValues) +912 System.Web.UI.DataSourceView.Update(IDictionary keys, IDictionary values, IDictionary oldValues, DataSourceViewOperationCallback callback) +179 System.Web.UI.WebControls.GridView.HandleUpdate(GridViewRow row, Int32 rowIndex, Boolean causesValidation) +1139 System.Web.UI.WebControls.GridView.HandleEvent(EventArgs e, Boolean causesValidation, String validationGroup) +809 System.Web.UI.WebControls.GridView.OnBubbleEvent(Object source, EventArgs e) +162 System.Web.UI.Control.RaiseBubbleEvent(Object source, EventArgs args) +56 System.Web.UI.WebControls.GridViewRow.OnBubbleEvent(Object source, EventArgs e) +118 System.Web.UI.Control.RaiseBubbleEvent(Object source, EventArgs args) +56 System.Web.UI.WebControls.LinkButton.OnCommand(CommandEventArgs e) +107 System.Web.UI.WebControls.LinkButton.RaisePostBackEvent(String eventArgument) +175 System.Web.UI.WebControls.LinkButton.System.Web.UI.IPostBackEventHandler.RaisePostBackEvent(String eventArgument) +31 System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler sourceControl, String eventArgument) +32 System.Web.UI.Page.RaisePostBackEvent(NameValueCollection postData) +244 System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +3824

Same is the case with Delete.

I'm not able to understand what went wrong.

 

Thanks,

Arshya
 

Source Click Here.