Well explicitly your error is telling you the problem. The value located in the field is not right.
For example if you have a coded domain, and the codes were "feet" and "inches" and someone put in "meters" or your code put "meters" into the field, and then it gave you an error.
Or another example is a range domain, where the only valid numbers that can be entered in are 1-9, but someone put in 10, and then you get an error.