Sometimes Remote assitance permission via GPO is not applied correctly. So we need to granting permission manually using registry. Below are the registry entry for granting Remote Assistance permission.
For Windows 64 Bit
Windows Registry Editor Version 5.00
[HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Policies\Microsoft\Windows NT\Terminal Services]
"fAllowUnsolicited"=dword:00000001
"fAllowUnsolicitedFullControl"=dword:00000001
[HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Policies\Microsoft\Windows NT\Terminal Services\RAUnsolicit]
"<Domain>\\<Security Group>"=""
For Windows 32 Bit (x86)
Windows Registry Editor Version 5.00
[HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows NT\Terminal Services]
"fAllowUnsolicited"=dword:00000001
"fAllowUnsolicitedFullControl"=dword:00000001
[HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows NT\Terminal Services\RAUnsolicit]
"<Domain>\\<Security Group>"=""
To use it you have to copy above code into notepad and save it using dot(.)reg extension. You also need to change the domain and the security group on the last line before you save it. Then you can run the reg file as an administrator using command prompt or just open regedit as an administrator and import the file.
