Here is what I do with a non-sucker. It requires a bit of work, but it is less stressful, and has worked for me every time.
I have never yet been able to force a calf to suck. If the instinct is not there, it seems it is not there.
So, rather than fighting with them, I simply tube them. Make sure they get at least one, and preferably 2 good feeds of colostrum in the first 12 hours. Then I move them to either cow's milk (if I can easily milk her) or milk replacer. Mama cow's milk is preferable, as it reduces the chance of you having problems with her accepting the calf later. But if she is really hard to handle, I go the easy route and use milk replacer.
Tube the calf for 2-3 days, depending on how strong it is. I usually feed 3 times a day, morning, early afternoon and mid evening. On the last day (day 2 or 3) I don't feed them in the evening. Leave the calf in a small pen with mama, and in the morning he should have gotten hungry enough for that instinct to kick in.
So far, this has worked for me every time I have had to do it. It is a pain in the butt, but it works. You don't get stressed, and you don't stress either the calf or the cow.
The reason I feed for 2-3 days, is to give the calf a chance to build up a bit of reserve, so that when you leave it overnight, it has enough strength to last the night, and to get up and look for dinner. If you were to do this on day one you may end up with an even weaker calf that you would have to mess with for even longer.
Some calves are oxygen deprived from a long birth and it takes some time for them to figure things out.
Some can be Selenium deficient, which causes muscles to not work correctly so a shot of selenium can be beneficial, and won't likely hurt anything.
