This is what worked for me. Make a <system.webserver> entry under <location path="ajaxpro"></location></system.webserver>
<location path="ajaxpro">
<system.webserver>
<handlers>
<add name="AjaxPro" verb="*" path="*.ashx" type="AjaxPro.AjaxHandlerFactory,AjaxPro.2" />
</handlers>
</system.webserver>
<system.web> <!--
<httphandlers>
<add verb="*" path="*.ashx" type="AjaxPro.AjaxHandlerFactory,AjaxPro.2" />
</httphandlers>
</system.web>
</location>
Add another tag at the bottom of web.config with the configuration tag:
<system.webserver>
<modules runallmanagedmodulesforallrequests="true">
<add name="ErrorHandlerModule" type="System.Web.Mobile.ErrorHandlerModule, System.Web.Mobile, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" precondition="managedHandler" />
</modules>
<handlers>
<add name="ScriptEngine.ashx_GET" path="ScriptEngine.ashx" verb="GET" precondition="integratedMode,runtimeVersionv2.0" />
</handlers>
<validation validateintegratedmodeconfiguration="false" />
</system.webserver>