Cu 2 setup problem!

hi

I get an error when installing cumulative update 2 for exchange server 2013. how to correct this problem ?

Error:
The following error was generated when "$error.Clear(); 
          $feVdirName = "PowerShell (Default Web Site)";
          $beVdirName = "PowerShell (Exchange Back End)";
          $vdirName = "PowerShell";
          $InternalPowerShellUrl="http://" + $RoleFqdnOrName + "/powershell";

          get-PowerShellVirtualDirectory -ShowMailboxVirtualDirectories -server $RoleFqdnOrName -DomainController $RoleDomainController | where { $_.Name -eq $beVdirName -or $_.Name -eq $feVdirName } | remove-PowerShellVirtualDirectory -DomainController $RoleDomainController;

          new-PowerShellVirtualDirectory $vdirName -Role Mailbox -DomainController $RoleDomainController -BasicAuthentication:$false -WindowsAuthentication:$true -RequireSSL:$true -WebSiteName "Exchange Back End" -Path ($RoleInstallPath+ "ClientAccess\PowerShell-Proxy");
          new-PowerShellVirtualDirectory $vdirName -Role Mailbox -InternalUrl $InternalPowerShellUrl -DomainController $RoleDomainController -BasicAuthentication:$false -WindowsAuthentication:$false -RequireSSL:$false -WebSiteName "Default Web Site" -AppPoolId "MSExchangePowerShellFrontEndAppPool";
        " was run: "The virtual directory 'PowerShell' already exists under 'EXC01.mydomain.local/Exchange Back End'.
Parameter name: VirtualDirectoryName".