Filter User Codes in EpiCombo by date

I want to use the Create Date in the UDCodes table to filter out any values whose create date > another date value in my form. Any ideas?

Full disclosure: We have an evolving product line that involves custom logic in the machine’s controller. We control the programming through Epicor by setting up a list of User Codes for each parameter. The programmer will then select each parameter from this pre-defined list. However, older versions of the controller can’t use values that didn’t exist in the version of the program installed on it. So I thought using the Create Date would be an ideal way to control this. I know how to filter to a static value - such as CodeTypeID. But how do I dynamically filter to a date that exists elsewhere in my form?

According to the references I’ve found, it should be as simple as:
include CreateDate in the EpiHiddenColumnsAppend array (a valid column in UserCodes)
include the following line in EpiFiltersAppend:

CreateDate < '?[Date03]'

It recognizes and accepts the syntax, but does not produce the expected results. All codes are still displayed.

Is it because I can’t run a ListDataSet with UDCodes? That’s the only difference I see between what I am doing and Jose’s youtube tutorial. Either that, or you can’t use the < operator…