Salve a tutti, spero che mi possiate dare una mano ho questo errore :

Object reference not set to an instance of an object.
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.


Exception Details: System.NullReferenceException: Object reference not set to an instance of an object.


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:




[NullReferenceException: Object reference not set to an instance of an object.]
Logistica.DPI.assegnaDPI.ddlutenti_SelectedIndexCh anged(Object sender, EventArgs e) +2121
System.Web.UI.WebControls.ListControl.OnSelectedIn dexChanged(EventArgs e) +118
System.Web.UI.WebControls.DropDownList.RaisePostDa taChangedEvent() +143
System.Web.UI.WebControls.DropDownList.System.Web. UI.IPostBackDataHandler.RaisePostDataChangedEvent( ) +10
System.Web.UI.Page.RaiseChangedEvents() +134
System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +5201

vi domando se e' possibile che sia qui questo errore :

lblaualificavalore.Text = dt.Rows[0]["qualifica"].ToString();
lblsezionevalore.Text = dt.Rows[0]["sezione"].ToString();

se si, vi chiedo gentilmente come potrei risolvere