How to hide an item in the drop down list at run time in VB.Net in VS 2010

HI,<o:p></o:p>

Can anybody help ?<o:p></o:p>

I have drop down list which is pulled from a table. I need to hide an item in the drop down list on the click of a checkbox on the form. THis is an app in VB.net and using VS 2010.<o:p></o:p>

I have used  the following code to hide it, and was working, NOw when I try to run it, it doesn't seem to work any more. Anybody know why ? <o:p></o:p>

Drp_Validity.Items(1).Attributes.Add("hidden", 1)<o:p></o:p>

I want to hide the item with the index 1.<o:p></o:p>

Any help will be much appreciated, and I have been playing with problem for a while now.

<o:p></o:p>

<o:p>Kindest regards,</o:p>

<o:p>DevSav</o:p>