DropDownList not registered with any event handler is triggering a different dropdownlist's selectedindexchanged handler
<p>I'm not sure why this is occurring but I have a breakpoint in the eventhandler which is only registered to dropdownlist A and every time dropdowlist B changes its selected index and causes a postback, the breakpoint is activated.</p>

<p>Dropdownlist B is should not have any event handlers registered to it.</p>

<p>Another oddity is that I created a fresh webform and simply copied the relevant code for the two dropdown lists into the new form and everything works correctly there.</p>

<p>What could be the reason that dropdownlist B triggers dropdownlist A's handler?</p>

<p>Edit:  I would post the code behind but it is fairly lengthy, even in just the relevant parts.</p>

<p>I did do a search for the phrase selectedIndex and I found it only in one place where I register it with the correct dropdownlist.  All of this is done programatically so the markup would not be much help.</p>

<p>Edit 2: </p>

<pre><code> DropDownList ddlname1 = new DropDownList();

                ddlname1.AutoPostBack = true;

                ddlname1.EnableViewState = true;

                ddlname1.ID = "ddlname1" + dex.ToString();
ddlname1.DataSource = nameODS1;

                ddlname1.DataValueField = "Card";

                ddlname1.DataBind();
</code></pre>

<p>These are the only lines in which ddlname1 (or dropdownlist B from the above discussion) are mentioned.</p>

<p>Edit 3:</p>

<pre><code>DropDownList ddlset1 = new DropDownList();
ddlset1.ID = "ddlset1" + dex.ToString();

                ddlset1.SelectedIndexChanged += new EventHandler(ddlset_SelectedIndexChanged);

                ddlset1.AutoPostBack = true;

                ddlset1.EnableViewState = true;
ddlset1.DataSource = setODS1;

                ddlset1.DataValueField = "Set";

                ddlset1.DataBind();
</code></pre>

<p>As requested, this is the code relevant to the other dropdownlist</p>

<p>Edit 4:  I just noticed something else which might be relevant.  Both dropdownlists are in the same update panel.  However, this is also the case in the test form I created for testing and everything works fine there.</p>
