Drop down menu for product custom fields

Hello,

I tried to make a product custom fields drop down menu for my product, but it still shows only a text, not drop down menu. I set Single Dropdown as a Field type in my new custom field but it still shows the text in one line.
I have "Display custom item fields" set to YES in configuration and in the product menu configuration.

here is the link for the product which I am trying to have with dropdown menu:
spikes.cz/prsteny/produkt/7703-pozlaceny...evnymi-pruhy-yxm1143
The dropdown menu should be: Barva: 1, 2, 3, 4, 5

Any idea why I cant get the dropdown menu?

Thanks
Vaclav

Hi Nicolas,

thank you for your reply.

Now I understand it.

I need my customer to be somehow able to choose from a product size and a color of chosen size. The problem is that some sizes do not have all the colors. You can see an example in attached csv. How can I make two drop down menus or a drop down menu and a check box...which behave like:
Customer select size 8 mm and the other menu changes and shows only blue color.
But when customer select size 10 mm the other menu will show blue, black and white color to choose from
When choosing 12 mm the second menu shows only white color available.

This is very important for me. How to solve it?

And for the item custom fields - is it possible to attach it somehow to only some products? It seems like it can be attached only to whole category/categories which I cant use as some product dont have the variants.

Thanks
Vaclav

Thanks Nicolas, that is what I was looking for.