اخطاء بكتب الوزارة فى اللغة الانجليزية!!!!!!!!

[MAZEN gamal]

WB p.75
I wish I ..........What I was doing at the weekend
Know- have known - Knew- was knowing
If we look at this sentence I think there is no correct answer
so in this case the only near answer is Knew
but how it can be explained
the sentence refer to past action so we should say had known
so is it a mistake