It's so frustrating isn't it? My DS1 LOATHED the pram, he never liked it when he was a bub and would start screaming almost as soon as he was in it. It made life very difficult!

Are you moving the pram (i.e walking around) when your DS starts to scream? The only way DS2 or DD would sleep in the pram is if it was moving. If it was stopped they'd just cry when they got overtired.