Please Help !

Hi,
I am having the Error in ASP.Net Application.
Can you go through this and send me the solution for the Error solving feedback.
Server Error in '/WBS' Application.
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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.]
Tariff3Tier.Frm_M_AddHotSpot.ViewHotSpotDetails()
Tariff3Tier.Frm_M_AddHotSpot.ddlHotSpotName_SelectedIndexChanged(Object sender, EventArgs e)
System.Web.UI.WebControls.ListControl.OnSelectedIndexChanged(EventArgs e) +108
System.Web.UI.WebControls.DropDownList.System.Web.UI.IPostBackDataHandler.RaisePostDataChangedEvent() +26
System.Web.UI.Page.RaiseChangedEvents() +115
System.Web.UI.Page.ProcessRequestMain() +1081

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Version Information: Microsoft .NET Framework Version:1.1.4322.573; ASP.NET Version:1.1.4322.573This is probably the most asked about error message and occurs when you are trying to use an object without instantiating it.

Make sure you have instantiated the object before referencing it in the code. If possible, please post your code here since it will be easier to identify the source of error.
We need more information ...
Please give use the code where the error happened ...

A recommendation: always check that your variables are not null !!!
Also, insert the following directive at the top of your aspx page -

<%@. Page debug="true" %>

and run it again.
Please don't post all of the code just yet... The debugger is telling you the problem is happening with this event: .ddlHotSpotName_SelectedIndexChanged(Object sender, EventArgs e)

Please just post the code that is contained in that event