You read wrongly the output.
In fact you have:

['zone', 'abigail', 'theta', 'form', 'libe', 'zas']
-2
LE RESULTAT EST zoneabigailthetaform
'zoneabigailthetaform' should equal ''

Your code is wrong somewhere.
Moreover:

• please give the langauge you are using
• before posting an issue look at the top of the page to see how many people passed the kata in your language (10767 in Python); when the number is not small chances are that your code is wrong or incompete. Instead of an issue post a question.