My puppy is fine when we're not home but...?

whines when we ARE home but not in his sight!!! we have a 15 week of apoo who is nearly housebroken. He is completely fine sleeping alone at night (he sleeps downstairs) and he's totally fine when we go to work in the morning. We have a dog walker that comes to let him out and walk him in the middle of the day. When we get home, and leave him in the living room to go to the kitchen that's when the whining and the crying starts!!!! It's as if we are home, we can't ever not be right next to him. We take him for a walk at night (at least 30 minutes), we play fetch, we give him affection, we train so I don't think he is suffering from separation anxiety. When he's left alone, he deosnt destory the house, he doesnt make accidents (if he has to go, he goes on the pee pad), i just don't know why he whines so much when we are home with him but not in his sight. Help!