problem : pop up window when exporting

Hello

I have a problem when i export my animation in animate cc. It works, but everytime, i have two panels that pop's up. It's benn going on for ages. i guess it come from the export option, but i'm a bit scared that i might mess up animate even more if i try to fix it myself. Notice that many months ago, i might have tried to change options in order to export in h264, then i left it like that... i don't really remember what i did, but that was stupid for sure ^^

this is my problem :

when i export ( ctrl+maj+alt+S)
i first have a pop up windows of information saying this :

" this animation uses fonctionnality that arn't working with the lecteur flash player 26. see "out" pannel for more details"

( i do updtae flash player )

and then another huge pannel ( all screen ) pop's up, like this, saying at every line : " the h264 video won't be published "

any idea how to fix this ?