drink? have they just been playing for a while? did they have a nap and are waking up now? they are going to have to relieve themselves soon.
take them to the place in the yard you would like them to use. this is a tip that many people may overlook. when you take them to "the spot" always follow the same path. this will begin to create an association between the path and what happens at the destination.
once you have arrived you may have to patiently wait for your puppy to do their business. choose a command word or phrase and repeat it so this also becomes part of the 