If you are unable to get a RegistryValueReturn to work with a REG_DWORD key, try the following steps as a workaround:

ShellCommandTextReturn(reg query HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\{AC76BA86-7AD7-1033-7B44-AA1000000001} /v language) 

I did this rule in my test environment and it worked like a champ. 

1. Open up regedit.exe 
2. Find the key that you want 
3. Right-click it and say "copy key name" 
4. In your customer invnetory rule, type: 

ShellCommandTextReturn(reg query <insert_clipboard_contents_here_minus_brackets> /v <insert_value_name_here_minus_brakcets>) 

5. Make sure to select the OS's that he wants the rule to apply to. 
6.Force an inventory on a machine to test. 


When mine worked, I got this under Custom Inventory Rules in my computer inventory: 

1) CUSTOM - Registry Value Return:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\{AC76BA86-7AD7-1033-7B44-AA1000000001} 
language REG_DWORD 0x409 

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