You need to replace the [ and ] you have around the whole filter with quotes.
try this: <$count filter="[tag[xx]tagging[]][tag[xx]]"/> -- You received this message because you are subscribed to the Google Groups "TiddlyWiki" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at https://groups.google.com/group/tiddlywiki. To view this discussion on the web visit https://groups.google.com/d/msgid/tiddlywiki/93cb57ef-b7ce-4a3d-bc94-db48543b751d%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
