Sticker Album in Merge Academy

For the past couple of days I have needed 1 final 5 star sticker for the lvl 12 sticker album folder. Today I finally collected the 300 stars needed to purchase the sticker pack that "garentees a lvl 5 sticker that you don't own yet". Once I purchased it I received several cards with only 1 being a 5 star sticker but it was 1 that I already owned.

Why didn't I receive the last sticker to complete the album?