*sigh* It works on the VM I'm running on the same computer but not on the computer itself. Don't you just love Technology?
I can see there's the hidden helper field with the rules on, so:
When you click the < button, the hidden helper field value is changed to "Back"
When the hidden helper field = "Back", the rules apply to roll the week data across to the left.
How does this manage to work for all the rows?
Queenie: I may have the body of a weak and feeble woman, but I have the heart and stomach...of a concrete elephant!
Partridge: Prove it!
Queenie: Certainly will! [picks up a tankard] First I'm going to have a little drinky...and then I'm going to execute the whole bally lot of you!