Adding Custom control in SharePoint 2010

1.Search for session in web config file of u r vertual dir
Maek enableSessionState="true"
eg: <pages enableSessionState="true" enableViewState="true" enableViewStateMac="true" validateRequest="false" pageParserFilterType="Microsoft.SharePoint.ApplicationRuntime.SPPageParserFilter, Microsoft.SharePoint, Version=14.0.0.0, Culture=neutral, PublicKeyToken=71e9bce111e9429c" asyncTimeout="7">

2. Make following line commented
<!--<remove name="Session" />-->

3. Make trust level full in bellow of  </siteMap> tag
    <trust level="Full" originUrl="" />
4. Put your custom control dlls into SharePoint vertual directory bin folder