Problem with interpolateBetween

[Dealman]

As I'm working on my new shooter, I decided to add a DX Progress Bar for the reloading, and use interpolateBetween to animate it.

However I have encountered something rather odd. Either I've missed something blatantly obvious, or I've found a bug with interpolateBetween...

Relevant Code;

local screenX, screenY = guiGetScreenSize() 
local barWidth = screenX*(485/1360) 
  
local isAnimatingStage1 = false 
local isAnimatingStage2 = false 
  
function example() 
    dxDrawRectangle(screenX*(438/1360), screenY*(714/768), barWidth, screenY*(44/768), tocolor(187, 0, 0, 255), true) 
end 
  
function handleAnimationStage1() 
    if(isAnimatingStage1 == false) then 
        isAnimatingStage1 = true 
        coolBarStart = getTickCount() 
        addEventHandler("onClientRender", getRootElement(), animateCooldownStage1) 
        setTimer(function() 
            isAnimatingStage1 = false 
            removeEventHandler("onClientRender", getRootElement(), animateCooldownStage1) 
            handleAnimationStage2() 
        end, 3000, 1) 
    end 
end 
  
function handleAnimationStage2() 
    if(isAnimatingStage2 == false) then 
        isAnimatingStage2 = true 
        coolBarStart2 = getTickCount() 
        addEventHandler("onClientRender", getRootElement(), animateCooldownStage2) 
        setTimer(function() 
            isAnimatingStage2 = false 
            removeEventHandler("onClientRender", getRootElement(), animateCooldownStage2) 
        end, 3000, 1) 
    end 
end 
  
function animateCooldownStage1() 
    if(isAnimatingStage1 == true) then 
        local coolBarNow = getTickCount() 
        local coolBarEndTime = coolBarNow + 3000 
        local coolBarElapsedTime = coolBarNow - coolBarStart 
        local coolBarDuration = coolBarEndTime - coolBarStart 
        local coolBarProgress = coolBarElapsedTime / coolBarDuration 
        local coolBarX1, coolBarY1 = screenX*(485/1360), 0 
        local coolBarX2, coolBarY2 = 0, 0 
        local coolBarNewX, coolBarNewY = interpolateBetween(coolBarX1, coolBarY1, 0, coolBarX2, coolBarY2, 0, coolBarProgress, "Linear") 
        barWidth, coolBarY1 = coolBarNewX, coolBarNewY 
    end 
end 
  
function animateCooldownStage2() 
    if(isAnimatingStage2 == true) then 
        local coolBar2Now = getTickCount() 
        local coolBar2EndTime = coolBar2Now + 3000 
        local coolBar2ElapsedTime = coolBar2Now - coolBarStart2 
        local coolBar2Duration = coolBar2EndTime - coolBarStart2 
        local coolBar2Progress = coolBar2ElapsedTime / coolBar2Duration 
        local coolBar2X1, coolBar2Y1 = 0, 0 
        local coolBar2X2, coolBar2Y2 = screenX*(970/1360), 0 --970 
        local coolBar2NewX, coolBar2NewY = interpolateBetween(coolBar2X1, coolBar2Y1, 0, coolBar2X2, coolBar2Y2, 0, coolBar2Progress, "Linear") 
        barWidth, coolBar2Y1 = coolBar2NewX, coolBar2NewY 
    end 
end 

Problem;

It's supposed to go from right, to left - and then when it reaches the far left(0) it should go back to the right again. However, the first stage is behaving very weirdly.

If I use the variable, barWidth it goes from full to empty, way too fast. However, if I use the actual calculation(screenX*(485/1360)) - instead of the variable, it moves much slower - but only reaches 50% and then it starts the 2nd stage.

What's weird is that barWidth should be the exact same as the actual calculation, as it's defined at the top of the script. And not changed anywhere else.

I've tried various durations and things but I can't pin-point what's causing this. The 2nd stage seems to be working as intended. Can anyone spot what I have missed? Or is this some sort of bug with interpolateBetween...?

[.:HyPeX:.]

I'm just reading over, but, if you make a value to go up (0 -> 1) for interpolate, how ur expecting to do the way arround (1 -> 0) with the same code?

[Dealman]

Thank you, but a friend helped me spot what I did wrong. Had coolBarNow instead of coolBarStart. x)