The default pattern is grey indeed, but you need to select the colour grey. If you don't give the pattern a colour, it won't accept it.
Hi there! Which design are you stuck on? And are you running version 2.0.1 or 2.0.0? Because the latest update (2.0.1) has made changes to the Masquerade Dress as well as the Opera Dress. They both now use a white colour for the sparkly pattern.
However if you're really stuck, click on the checklist, which should be the last tab! This should show you what's missing and what isn't. The checklist is only available in version 2.0.1, so you'd need to have updated the game to get the checklist.
