Intentionally or not, Facebook has set up tagging so that you must *like* the page you are trying to tag as the page you are tagging from. In the case of Vintage Lovers Unite, she *liked* the page as a personal page. When she tried to tag the page using the business page it didn't work.
To fix this, she had to use the page as Vintage Lovers Unite and *like* The Vintage Cupboard and High Falootin' Junk as Vintage Lovers Unite. Then she was able to tag.
I hope this will save someone hours of frustration. You see, I also run Vintage Lovers Unite as a way of trying to build a community of others who like or sell vintage and/or shabby items. I thought I was pretty Facebook savvy until this tagging problem began to show up.
Maybe it's been this way all along but wasn't a problem for me until recently. Happy tagging!