c# registrykey is null
// A 32-bit application on a 64-bit OS will be looking at
// HKLMSoftwareWow6432Node node by default.
// To read the 64-bit version of the key,
// you'll need to specify the RegistryView:
var hklm = RegistryKey.OpenBaseKey(
RegistryHive.LocalMachine, RegistryView.Registry64));
var key = hklm.OpenSubKey(
@"SOFTWAREMicrosoftWindowsCurrentVersionUninstall"));