Minor bug fix

When email field is left empty (And it is marked reqd) it gives error => "Enter a valid email address" instead of "Email field required" or something like that.
{
http://demo.eden.sahanafoundation.org/eden/hrm/staff/create
Fill the required fields except email.
}
What's wrong with the error_message? And if you replace it, then why don't you remove the original one?