Help!

[aduprey]

I have a 9 year old EXTREMELY mellow, super obedient yellow lab. However, my roommate has a 9 month old beagle/walker hound mix who is crazy!
He (Mulligan) could be a really great dog, but is the type that NEEDS a TON of attention when it comes to training. Since my roommate works a lot and doesn't have the time necessary to spend with him I am going to try.
Okay, my biggest pet peeve is he has no concept of the come command. Example: I get home and let him out of his crate and straight outside to do his business. I let him in after this and he goes straight upstairs and will not come to me when I call him. I had treats in my hand and a clicker. He would walk to the edge of the stairway. When I could see him I would praise him enthusiastically, but he would turn and walk away. We did this over and over for 15 minutes until I couldn't wait anymore. I had to leave so I went upstairs and had to pull him by his collar back downstairs.
What is the best way to handle this? We've practiced when we're both downstairs by calling him over and over and over and praising him and giving him treats, but what do I do when he's upstairs and won't come??? I feel like he's not going to like me after I have to drag him down. You're wondering why he doesn't want to come downstairs arent you? He is in his crate from 8am until 5 or 6. (he gets to go out at lunchtime). Any suggestions would be helpful and don't think this is the last of me!! We have a TON of work to do!!!!