My app running on II7 is not logging errors.  I do get the elmah.axd page, but no records 

<sectionGroup name="elmah">

<section name="security" requirePermission="false" type="Elmah.SecuritySectionHandler, Elmah"/>

 <section name="errorLog" requirePermission="false" type="Elmah.ErrorLogSectionHandler, Elmah"/>

<section name="errorMail" requirePermission="false" type="Elmah.MailSectionHandler, Elmah"/>

 <section name="errorFilter" requirePermission="false" type="Elmah.ErrorFilterSectionHandler, Elmah"/>

    </sectionGroup>

  <elmah>

 <security allowRemoteAccess="1" />

<errorLog type="Elmah.XmlFileErrorLog, Elmah" logPath="~/App_Data" />

  </elmah>

On System.Web HttpHandlers:

<add verb="POST,GET,HEAD" path="elmah.axd" type="Elmah.ErrorLogPageFactory, Elmah"/>

On HttpModules:   <add name="ErrorLog" type="Elmah.ErrorLogModule, Elmah"/>

 <system.webServer>   

<validation validateIntegratedModeConfiguration="false"/>   

<modules runAllManagedModulesForAllRequests="true">         

<remove name="ErrorLog"/>      

<add name="ErrorLog" type="Elmah.ErrorLogModule, Elmah" preCondition="managedHandler"/>   

</modules>   

<handlers>

 <add name="Elmah" verb="POST,GET,HEAD" path="elmah.axd" type="Elmah.ErrorLogPageFactory, Elmah" reCondition="integratedMode"/>

  </handlers>  </system.webServer>