Housebreaking a 5-month old puppy

Question
My daughter purchased a 5-month old Havanese puppy from a pet store, so being in a cage is all he's known.  We are trying all the standard ways to get him to go outside.  Taking him out first thing in the morning, as soon as he comes out of the crate, after meals, etc.  We keep him out 20 minutes- 1/2 hour.  All he does is smell and then goes inside and pees on the rug or does both in his crate.  We even use wee-wee pads outside.  What next?

Answer
Get him out on leash after melas after drinking after playing for long period and after naps....keeping him on a short leash will make sure he smells around and goes  within 5/10 minutes...leaving him roam teh ayrd for a half hour only gives him time to semll around then hes called in and of course pees in the house...also a dog that is this young being left outsdie for 15 minte to hafl hour periods without supervision or guideance may begin to think that the yard is for play and exercise and not for pottying at all and in turn goes as soon as it comes inside. Try the leash thing this is what i used for my small dogs as puppies....after about 6 weeks of this he should be fine for good.