How long has he been at this daycare and what kind of responses are you getting from his teachers regarding his naptime problems?
I have worked at a number of different centers and now have my own home childcare business, so have seen a lot of different napping issues. Sometimes it's because the child has not had adequate activity to make them tired by naptime. He also might just be overstimulated by being around all the other children. Perhaps they don't have a good routine for napping. At his age, most daycares won't be using cribs for napping, and from what you've said I'm wondering if they have regular cots or mats for the children. Most centers use one or the other and all children sleep on the same thing. Only bed babies (up to a year of age) normally are put into cribs.
Do the teachers put on quiet music and have a calm room for the children to rest in? Do they sit with the children and rub backs or do any other type of soothing routine to help the child sleep?
Are there teachers in the room trying to do other jobs as the children are trying to settle down? If so, they need to stop and help get the children settled and asleep before doing those jobs. And no traffic in and out of the room to disturb the children from settling down.
Another thing to remember is that he may just not have been there long enough to feel 'at home' and comfortable with the new surroundings. If they are gentle and calm with him, he should be able to eventually trust them enough to sleep there.
I would highly recommend that you simply drop by and observe one day at their nap time. Don't enter the room, but look in through a window.. and most centers will have a window that you can look through to see what's going on with your child. Frankly, if they don't I'd be looking for another place for him, where I could observe activities without the child seeing. This is one way you can assure yourself of how your child is responding as well as to see how the teachers are treating him. You may be able to detect something that will help you give the teachers some good ideas of what they can do to help your child sleep better too.
One more thing... at seventeen months of age, I have often observed a changing in napping patterns in children anyway. They go from falling asleep the minute their head is down, to having to toss and turn, or fight sleep for a while before giving in. This could just be one of those adjustment periods and the teachers as well as you may have to learn how to help him make the adjustments and get back into napping well.
