So, Tucker is 16 months old now, and has been doing his business the whole time in our backyard- on grass.
Hubby has finally completed a 8X50' fenced in dog run for Tucker to do his business in one restricted area (to make clean up easier, and save our grass), but its cement patio tiles. Its a beautiful dog run, shaded, but Tucker will not #1 or #2 on the cement!

We put some of his recent #2's in the dog run, thinking the smell would give him the idea it was ok to go there, but nope.

I was off work yesterday (Canada Day) and my plan was that Tucker would pee when he really needed to pee, so he spent the entire day in the dog run,(well, going in and out of the house into the dog run- but not allowed onto the grass) with me keeping an eye on him, ready to shower him with praise and cheese the second he did his business...but he never did.

He held it for about 11 hours! Hubby and I felt just horrible, and we could see him stressing out, a few times he'd pace and look like he was just about to pee....but then he'd change his mind and stand in front of the gate that would give him access to the grass.
Finally, as we were entering the better part of the 12th hour, we decided to let him into the grass to go (I'm sure it can't be good for him to be holding it that long, and believe me we were feeling guilty as heck about it) BUT I went with him, and used an old juice pitcher to "catch" the pee. I then was able to pour it out inside the dog run, to get the smell there. I ended up doing this about 3 times last night, to "mark" different spots on the cement floor, hoping the smell would intice him to pee the next time.
Anyway, this morning, Tucker is back outside, restricted (for now, we'll have to go to work soon) to the dog run- but is still not going.
Any advice or ideas on how to potty-train to go on cement after a year and a half of going on grass?? It is frustrating all three of us!
Thanks, and sorry about the lengthy post.
-Sarah