Possible to breed after not breeding goat does for 3-4 years?

We haven't been able to get our goat does to be bred for 3-4 years. Will this present a problem in getting them to settle?
I've had elderly parents that I couldn't leave, but I can take the does to the buck next year. I want to know, am I wasting my time?
Have I lost the ability to have pregnant goats and milk?

How old are the goats? What were their previous pregnancies and births like?