Cascading dropdown in ASP.Net is not working fine
<p><img src="http://i.stack.imgur.com/FZhGV.png" alt="Cascading dropdown using ASP.Net"></p>

<p>Hi - I know this sounds simple, but I am having trouble with some functionality to be achieved. Please refer the attached screen shot of the situation. This is what I am doing:</p>

<ol>
<li>On page load I am loading the first drop down of Product / Service</li>
<li>BAsed on the selection of the Product dropdown I am populating the second dropdown "Category". I am making the database call to make this happen.</li>
<li><p>Based on the selection of the Category I am populating the third drop down of the price. I am making database call to get the information for this drop down.</p></li>
<li><p>Based on the selection of third (Price) dropdown, I am hiding / showing the panels.</p></li>
</ol>

<p>Each dropdown is doing a post back to make the call to the datbase to get the details for the subsequent dropdown.</p>

<p>Everything seems to be working during first run, but the problem comes when I try a combination of the drop down. Following are the problems I am having:</p>

<ol>
<li>Panel once rendered doesn't go away if I select different option from Dropdown1 and 2.</li>
<li><p>After subsequent run, the values are added up after each post back. For example if I have a product "Toy Car" in the product / service dropdown, it is now appearing twice and so on.</p></li>
<li><p>If the user selects the default option "Select Product", "Select Category" etc. The entire hierarchy should be reset. For example if the previous selection in the Product dropdown was "Toy Car", and now I select the default option "Select Product". It should reset "Category", Price and Panel visibility.</p></li>
</ol>

<p>Please let me know how this can be done. </p>

<p>Thanks for the help.</p>
