Detecting Registry Values

I am trying to write an install script. During installation, I want script to check if Windows Mobile Device Center has been installed.

following from the example in NSIS

ReadRegStr $0 HKLM Software\NSIS ""
DetailPrint "NSIS is installed at: $0"

I write
ReadRegStr $0 HKCR Installer\Products\DC276626FCFB9A94EAEFBAF0DEB3CFB5 ""
DetailPrint "Windows Mobile Device Center is installed at: $0"

That fails.

I am looking for the right script that will let me know that the application has been installed, hence no need to install it.

Those keys don't seem to have a default ("") value, try "PackageCode"