Check for particular software existence

RegistryKey hklm32 = Registry.LocalMachine;
hklm32 = hklm32.OpenSubKey(@"SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\{4AF99FCA-1D0C-4D5A-9BFE-0D4376A52B23}");
Object obp = null;
if (hklm32 != null)
{
obp = hklm32.GetValue("InstallLocation");

if (obp != null)
{
RevitInstallationDirectory = obp.ToString();
isInstalled = true;
}
return isInstalled;
}