ASP.NET not seeing Radio Button value change

<span style="font-family:Verdana;font-size:8pt;background-color:red;Disabled:true;">
<input id="ctl00_MainLayoutContent_WebPanel4_rbSolid" type="radio" name="ctl00$MainLayoutContent$WebPanel4$DetailType" value="rbSolid" onclick="styleLookupChanged(this);" />
<label for="ctl00_MainLayoutContent_WebPanel4_rbSolid">Solid</label>
</span>