After ten days, if she lived here, she'd be behind the barn with the bulls waiting for a trailer ride. The calf would be on a bottle waiting for a good mother who had some bad luck, or a good sport waiting for an extra "twin". We used to muck around with cows like that, and even had them take the calf after fighting for way too long, but since BSE, our tolerance level for that has dropped.
If you really want to keep trying, I'd recommend feeding her some grain every time the calf sucks. After a while she will associate the two, and it will get easier and easier. Then after that, the calf will become strong brave and pushy enough to fight for it. Oxytocin can become a crutch, but if you only use it a couple of times, who knows, it may make a light come on in her little mind.
But I'd still get rid of her in the fall. She's obviously hormonally challenged.