new apps purchased on ipad not synching with iphone 4S. This a new problem. No problem in the past

Purchased new apps on ipad. Purchases did not synch with iphone 4. Purchases are listed in my itunes account and on my ipad, however, they are mot listed as purchased on iphone 4s. this is a new problem. I did not have any probelms in the past wit apps synching with iphone 4.