text box validation rule on a form
	
	
		I have 2 fields on a form that if the sum of these 2 fields go over the limit I want to give the user an error message.  On the 2nd field I am summing the 2 field together in the validation rule  =[Runtime_minutes]+[NoWork_minutes] <>480 ,  but it doesn't send the error message.   I have also tried to add the form to the equation and I get the object doesn't contain the automation object error.    What am I doing wrong?   I thought it would be a simple addition.   Thanks for your help on this.