code will not work if i add if statement?

i have a gas mask gui i want to appear when you equip a tool. I have that set up. However, I am also making a bar appear when you equip the tool and when the bar is completely filled up, the gui will appear on your screen. here is my code:

if script.Parent.Parent.bool == true then
	while true do
		wait(0.25)
		MeterA = MeterA + 1
		if MeterLocation:FindFirstChild("Meter"..MeterB) then
			MeterLocation["Meter"..MeterB].ImageTransparency = 0
			MeterB = MeterB - 1
		end
				if MeterA == 19 then
		script.Parent.Visible = false
		MeterA = 0
		MeterB = 19
		end
		end
		end

see, the code works fine UNTIL I add the if statement, even if the value is true. there are no errors in output. Help would be helpful