10 < $$up ≤ 50
FM does not support this syntax. Use
$$up > 10 and $$up <= 50
Ahh, of course, thanks I'll try that out now.
Aaaaaand it worked :)
What Wim said.
Also, the test in this form in an End If 
10 < $$up and $$up ≤ 50
is not necessary; if you have reached that point, you already know that $$up is larger 10.
And lastly, unless you need to be very explicit in your script, you can use a single
Set Variable [ $$up ; with the calculation
$$tw ≤ 10 ; tab_customerprices::_10 ;
$$up ≤ 50 ; tab_customerprices::_50 ;
$$up ≤ 75 ; tab_customerprices::_75
// and so and and so forth
where Case() uses the result of the first test that evaluates as True (same as If / Else If).
(For some reason, your description only mentions one $$var, but your code has two …)
Thanks for the tip! Now my script works so I don't see a reason to change it now, but I'll definitely use that tip to make it easier in the future, I'm actually making a script that now that will automatically calculate field related to the field being changed when you exit it with a Get ( ActiveFieldName ) variable performing the calculations for the respective fields in the correct order when x field is changed, I'll try out the Case step then
And yea, hehe, the last bit was a typo on my hand, I don't know how to copy a script out of FM so I just wrote it down as best as I could, ended up with a bit too many $up calculations, hehe, but the actual script doesn't look that way, luckily I
Speaking of, now that I'm on the topic and got your attention, do you by any chance know if it works to perform a step:If [$field = FieldName]Set Field [FieldName; Field 1 * Field 2]Because right now, this doesn't do the trick for me.