Sort product with symbols

Question

Hey, I have been working for a few hours now with substitute and it behaves perfectly so far! However, now that symbols which were initially indices appear in the main expression, there seems to be a problem with sort product. I am attaching below a sample piece of code:

{\dagger}::Symbol.
{a,b,c,\alpha,\beta,\gamma}::Symbol;

{P^{\dagger}_{a? \alpha?}, K_{a? b?}}::NonCommuting.

{a?, x_{a?},P^{\dagger}_{a? \alpha?}, K_{a? b?}}::SortOrder;

ex:=K_{a b} a x_{a} P^{\dagger}_{b \alpha};
sort_product(_);

In this case the expression remains unchanged, although the c-numbers a and x_a should be taken to the left. Am I missing something?

Thank you!

Comments

They are; for me the output is

$$a x_{a} K_{a b} P^\dagger_{b\alpha}$$

If that's not what you got, there must be some other properties which interfere with your sort order.

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Yes, you're absolutely right, I don't know why it didn't work for me that time, maybe I didn't restart the kernel after putting a? in the sort order definition or something. It works now! Thank you, sorry for the trouble!