Validation Conditions


We are working to create simple validation conditions such as if a child’s age is under 6 months then the child cannot be enrolled. We only been using 1 user and we have been working on multiple computers, sometimes at the same time, but never on the same form. When we will log back in a day or so after working the validation condition that was once entered has been deleted (and not by the other person who is working from the other computer). What could be the reason for this?