Why Doesn't the Annotation Function Work in SumatraPDF 3.5.2 (64-bit)?

[pipi4]

Why can't I use the annotation function in SumatraPDF 3.5.2 (64-bit)?
I can't find the annotation op
tion, whether I use the "A" shortcut key or right-click to annotate. Even though I see the annotation color settings in SumatraPDF.settings.txt, I still can't add annotations. Can anyone explain why? If the annotation function is not available in version 3.5.2 (64-bit), which version supports highlighting and annotations?

[GitHubRulesOK]

That is unusual (but do seem to remember seeing something similar once before) it should appear lower down, when the PDF selection is valid, perhaps it is not a true PDF file?

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[pipi4]

Thank you! I see now that it can only annotate PDFs.