6 month old puppy wont go to the bathroom outside

Question
About a month ago we adopted a 5 month old cocker spaniel mix (we believe that he has daschund in him).  He is only about 11 pounds now.  I live in Vermont and we recently went through a spell of temps well below zero.  Joe gets very cold and shivers when it is cold, so we did buy him a sweater.  He is currently paper trained, mostly due to the weather.  Now that it is warming up, we are trying to housetrain him.  He absolutely loves to go outside for walks and to go for rides in the car...but refuses to go to the bathroom outside.  He is a puppy that can hold it forever, and is very stubborn about it.  This is a typical example of our efforts: yesterday I took him for an hour long walk, and then took him to the spot that we would like him to go to the bathroom.  Stayed there for a little while but he did not go.  Brought him inside and within 10 minutes he had gone pee and poop.  So, I thought that I would try after dinner.  Waited until about 10 minutes after he ate (as he never goes right after eating), and went outside with him.  I stayed outside with Joe for 30 minutes, and nothing happened.  I was prepared with a treat to praise him, but it didn't happen.  Brought him back inside and he went on his papers (not as quickly as usual).  The real situation was this morning.  We have him crate trained and he is very good about not going in his crate, and he always goes on his papers within 10 minutes of waking up.  So, before he was fully out of his crate I had the leash on him and then brought him right outside.  We stayed outside for probably 20 minutes, and even brought his papers to the spot, thinking that might jog him to go.  Brought him inside, and then back out 10 minutes later.  Decided to give him his breakfast, thinking that might help the situation, and the tied him up outside for about 15 minutes (he seems to be too distracted when we are there).  Went out to get him, and nothing.  We are now about an hour after waking, and I know that he needed to go!  Brought him in the kitchen, where he usually stays, and did not bring in the papers.  He of course peed all over the floor - which we thought would happen.  Used our go pee phrase over and over, and brought him out to the papers in our entryway...thinking we might need to do babysteps, and praised him while he was on the papers.  He is now in his crate for the day (my husband will take him out at 12:00.  Sorry for such a long description.  I just feel like we are doing what the training resources say, but he is not budging.  What are your suggestions?

Answer
The more details you post, the less likely I am to suggest something you are already doing.  Still, I do need to go over some details. Choose a command and spot you want it to use.  When you go out, take it to the spot and give it the command in a firm, but friendly voice. Keep repeating the command and let the puppy sniff around. If it does anything, praise it. Really let it know what a good dog it is and how much you love it, and maybe a treat.  If it doesn't go, take it inside and give it a drink and any meals scheduled.  A young puppy will need to go out immediately afterward.  Go to the spot and follow the above routine. Praising it if it goes is extremely important.  If it doesn't go, take it back inside and put it in its crate and try again soon.  Do not let it loose in the house until it does go.  This could take some time.  Try playing a vigorous game of fetch or something.  He could get so busy and need to go so bad, he will forget waiting to go inside.  

You might also try a sheltered spot more like inside, and away from where you play with him.