Getting a question mark on a tag placement? It could be a couple of things but this avenue will be related to nested families. First off if you are tracking nested families in a schedule make sure to mark them as shared before nesting them. Otherwise you will have a physical representation but it will be hidden otherwise from tags and data.
Once in a file the host family will result in a tag. If the parameter, you are tracking in the tag does not exist you will get a question mark. To tag through the host family you just need to activate the tag and tab over the item you want to tag. sometimes as group assortments of child families into a host you will want this feature to get down to nuts and bolts.