function ValidateData() {

//Submission variable
var CanSubmit = false;

//Check to make sure that the worksheet title field is not empty.
CanSubmit = ForceEntry("WorksheetTitle", "Please enter a title for the worksheet.");
if (!CanSubmit) return;

// check numeric entries are numeric 
CanSubmit = ForceNumber("QuestionCount", "Number of questions");
if (!CanSubmit) return;

CanSubmit = ForceNumber("BaseRangeLower", "Starting number (lower range)");
if (!CanSubmit) return;

CanSubmit = ForceNumber("BaseRangeUpper", "Starting number (upper range)");
if (!CanSubmit) return;

CanSubmit = ForceNumber("RangeLower", "Numbers to subtract (lower range)");
if (!CanSubmit) return;

CanSubmit = ForceNumber("RangeUpper", "Numbers to subtract (upper range)");
if (!CanSubmit) return;


//Only check operand range if checkbox is ticked
if (document.getElementById("Operand Range Checkbox").checked) {
		
	CanSubmit = ForceNumber("OperandCountLower", "Problem length (lower value)");
	if (!CanSubmit) return;
	
	CanSubmit = ForceNumber("OperandCountUpper", "Problem length (upper value)");
	if (!CanSubmit) return;
}

//Only check trailing operand if checkbox is ticked
if (document.getElementById("Trailing Operands Checkbox").checked) {
	
	CanSubmit = ForceNumber("TrailingOperandsValue", "Trailing value");
	if (!CanSubmit) return;
}

//Only check mutiplier if checkbox is ticked
if (document.getElementById("Multiplier Checkbox").checked) {
	
	CanSubmit = ForceNumber("MultiplierValue", "Multiplier");
	if (!CanSubmit) return;
}


// check question range
if (parseInt(document.getElementById("QuestionCount").value) < 1 || parseInt(document.getElementById("QuestionCount").value) > 99)  
  { 
  alert ("Please enter a value in the 'number of questions' box between 1 and 99."); 
  CanSubmit = false;
  return; 
  } 

//If fields have been entered correctly, submit the form
if (CanSubmit) document.LayoutSubtraction.submit();

} //end function