run time error in Forms Authentication

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C#

when open my website and log in in my CMS(admin page) for the same website at the same browser at the same time get this error in the web site http://www.tawjihiacademy.com/error1.jpg[^]

and folder CMS web.config contain

<configuration>
   <system.web>
     <authorization>
       <allow roles="admin"/>
       <deny users="*"/>
     </authorization>
     <pages theme="Admin" />
   </system.web>
 </configuration>

when create folder in my site EX(test) that contain web.config file
web.config file have code same as the above one
this mean that admin can enter in folder but in same time get this error in the web site http://www.tawjihiacademy.com/error1.jpg in same browser.