why is this incorrect

You are soooo close! You just mixed up display_menu and menu.

Try this:

available = "banana split;hot fudge;cherry;malted;black and white"
sundaes = available.split(';')
menu = ', '.join(sundaes)
display_menu = "Our available flavors are: {}".format(menu)

EDIT: You also used the join function incorrectly. You must call the .join() method on the separator string, then pass in the list to the split method. It's strange, but you kinda have to get used to it.

Also, I just noticed that you have an extra period after the {} in display_menu's string. Code challenges are super-picky and won't even except that to pass. Keep this in mind!

I hope this helps. ~Alex

Don't forget to mark this answer as a Best answer if it helped you out! Thanks!

When using the join method, the string you would like to use to separate the items goes first, then the list goes in brackets. So play_menu = ", ".join(sundaes) should give you the desired result.

You will also need to make sure you assign a value to variable display_menu before printing it (i.e. your 4th line should come before your 3rd).

Edit to add: Alex beat me to it, I agree with his solution.