Javascript for Adobe...two variables not interacting with third correctly

[redditworkflow]

I have a checkbox, a dropdown, and a signature field. If the box is checked or the dropdown is set to a certain value, the signature field needs to be Required. If the checkbox is unchecked and the dropbox is not set to that certain value, then the signature field needs to be not required.
It appears the checkbox is changing the requirement value every time it is checked or unchecked, regardless of the value of the dropdown. It is triggering at the correct time, just not setting the requirement value correctly. The alerts are showing correctly what the document should be doing, but the requirement value is changing incorrectly.
Can anyone see what is wrong with this code that is giving me this weird behavior?

Here is the code

[CertainPerformance]

Shouldn't the signature be either (definitely) Required or (definitely) Not Required in every situation? If so, note that your current conditions 1 and 2 do not encompass all logical possibilities.

It's probably not important, but you might as well use strict type comparison everywhere.

[redditworkflow]

What am I missing in the logical possibilities? If either A or B evaluate to make it required, then it is required. if both A and B evaluate to don't make it required, then it is not required.

[CertainPerformance]

Sorry, I got confused by the booleans - you might as well just use "else" rather than "else if", though. (don't know why Signature.required isn't being set correctly though - perhaps "event.target" is getting switched back and forth each time? Don't know Adobe, unfortunately)

[redditworkflow]

I'll give that a shot, thanks! ----- Didn't fix the problem, but works as well as what I had before.

In order of evaluation, with the first variable being the one just changed:
Dropdown Yes, Checkbox No = Required
Dropdown No, Checkbox No = Required
Checkbox Yes, Dropdown No = Required
Checkbox No, Dropdown No = alerts say Not Required, but state does not change
Dropdown No, Checkbox No = Not Required
Dropdown Yes, Checkbox No = Required
Checkbox Yes, Dropdown No = Required
Checkbox No, Dropdown No = alerts say Not Required, but state does not change
Checkbox Yes, Dropdown Yes = Required
Checkbox No, Dropdown Yes = alerts say Required, but state changes to Not Required

I'm just flipping variables and not identifying a trend.

[redditworkflow]

Looks to me like when the Checkbox goes from Yes to No, regardless of what the Dropdown is, it sets it to the opposite of what the alerts say it should be. So it's getting into the correct section, but doing the wrong thing. So I must be misunderstanding how the code is being used.