Looks like you need to call InitCommonControls(Ex), in addtion to the manifest. https://jeffpar.github.io/kbarchive/kb/309/Q309366/ I'll forgive your slight misremembering, because it's probably been 20 years.
Often all you need is the manifest. If the app won't run at all after you have added the manifest, then add a call to InitCommonControls(Ex)