"If you are happy, I am also happy."
Translation:Se vi estas feliĉa, ankaŭ mi estas feliĉa.
I've just tried it and it is not accepted. It surely should be, as there is nothing to show whether the "you" is singular or plural. I have reported it.
I answered "Se vi feliĉas, mi ankaŭ feliĉas." and it was marked correct. It's possible that they didn't account for that particular word order. It should be correct.
Edit: I got this phrase again and this time answered "Se vi feliĉas, mi feliĉas ankaŭ." It didn't get marked wrong, but I received the following message: "ankaŭ always goes before the word it refers too, so in this case needs to go before "mi" "