Code working in Powershell ISE 2.0 but not ISE 4.0 - powershell-2.0

Question

The following code open a random number generator, selects the button to run the generator, and returns a random number.
#Start-Process
$ie = New-Object -com InternetExplorer.Application
$ie.Navigate("https://www.random.org/widgets/integers/iframe.php?title=True+Random+Number+Generator&buttontxt=Generate&width=160&height=200&border=on&bgcolor=%23FFFFFF&txtcolor=%23777777&altbgcolor=%23CCCCFF&alttxtcolor=%23000000&defaultmin=1&defaultmax=100&fixed=off")
$ie.visible = $true
echo "Random.org opening"
while( $ie.busy){Start-Sleep 1}
sleep 10
echo "Random.org open"
$FindBtn = $ie.Document.getElementByID("true-random-integer-generator-button").click()
sleep 5
$result = $ie.Document.getElementByID("true-random-integer-generator-result").innerHTML
echo $result
This works fine for me in powershell 2.0, however, when I run in 4.0, iget the following errors:
You cannot call a method on a null-valued expression.
At line:13 char:1
+ $FindBtn = $ie.Document.getElementByID("true-random-integer-generator-button").c
...
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo : InvalidOperation: (:) [], RuntimeException
+ FullyQualifiedErrorId : InvokeMethodOnNull
You cannot call a method on a null-valued expression.
At line:15 char:1
+ $result = $ie.Document.getElementByID("true-random-integer-generator-result").in
...
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo : InvalidOperation: (:) [], RuntimeException
+ FullyQualifiedErrorId : InvokeMethodOnNull
What is the reason behind this? Is there a big formatting difference between powershell 4.0 and 2.0? 4.0 is on a different VM to 2.0, could that be having an affect?