Base: table widget in form shows combobox. How to make so?

Hello.
I am learning to make DBs with Base, and i took an example from LO wiki : https://wiki.documentfoundation.org/images/a/af/Media_without_Macros.odb

Here, when I open Reader_Admission form, i can add readers to table control widget. There is Gender field in the table, where I can select value through combobox - male or female. However, data source for the form is a query called Reader_Input_Filter. This query contains only Gender_ID field. This field is linked with Gender. So it is somewhere set, that this table could show the field, using values from other table.

I wanted to implement the same. however, it doesn’t work so. In my table it doesn’t substitute ID fields in table with combobox containing values from other table. So I can’t select variant of value from other table, I could only enter the ID manually. Links in relations editor is set. I can’t post my test DB because my rating is not enough (just registered). The only difference I see, is that Gender table in example has TINYINT type of primary key, while my example has INTEGER. I wonder, if it could be the reason?

LO version: 4.2.3.3
OS version: Ubuntu 14.04 64 bit