PLease help?? toddler coming out of naps and night sleep?

Hi there my son is 2 years old and he is a great sleeper goes down at 10 and sleeps till half 9 or so, he then goes for nap at 130 till 330. the only way he goes for his sleeps is rockin him in my arms and poppin into cot when he is asleep, i don't mind doing this but lately his morning nap i would get him asleep and when i would reach his cop he would wake up crying and ive to bring him back out to sit him on me and i may forget about putting him into cot then. but night time use to be fine min he go asleep yea could pop he in but last night he woke up and screamed the house down. what should i do if this happens tonight, do i leave him crying cause if i bring him back out at rock him and again nce he goes asleep i try put him in it happens again.. please help me as i don't no what to do and have never had a problem in putting in to bed??? is he to old to be rocked??