Might sound stupid, but have you put them on the correct arms. The fitting for the drivers side is a bit different for the fitting on the passenger side.
I bought my replacement blades from Peugeot. They incorrecty marked the boxes as near side & offside (found out later it's a French thing - other way round to us).
So I fitted one - went on fine, the other went on mostly, but wouldn't click into its locked position. I tried for ages & eventually went back to my dealership, where they couldn't get it to fit either & were going to order in another blade when a mechanic said swap them round, so we did & both went on fine.
Just a thought anyway :eusa-think: