Why is wrong?

Question

Bonjour,I started learning l'iparfait and I cannot understant why my answer in bold is worng, as far as I can imagine the other anwer in italics is wrong. Could you please explain??

"Tu sortais de la boulangerie quand ma mère t'a vu." means:You were coming out of the bakery when my mother saw you You came out of the bakery when my mother saw you

Accepted Answer

Hi Apostolos, 
I don't understand as having checked the question the answer in bold is the correct one -
You were coming out of the bakery when my mother saw you 
it should, therefore,  be accepted.
If this is not the case, please use 'Report an issue' on your correction board as there may be a glitch.
Just to reiterate -
You came out of the bakery when my mother saw you 
is wrong.

Answer

Hi Apostolos,On the face of it, I cannot fault what you say you had written "Tu sortais de la boulangerie quand ma mère t'a vu.""You were exiting/coming out from the bakery when my mother saw you." I see this as an acceptable translation and correct use of l'imparfait.

Answer

Jim ,In your answer I believe you have flip-flopped the incorrect conjugation if you wrote t'a instead of t'as.  It should be t'a  to agree with mere, (not tu.)Bonne continuation !  I always enjoy your explanations.

Answer

@ CaryThanks for pointing out my error  --  you are absolutely correct the subject is mère and the conjugation should be t'a vu.Thanks also for your kind comments - I am pleased to find that I am helping along the way in general.Bonne journéeJim