Static url variable is not found in POSTMAN request

I want to define a custom static url for my connections in Postman:

Then I tried calling a GET request by that custom static url:

But I get Could not send request message because the variable is not defined somehow:

But I don't know why it can not be found since I have defined at Variables section of the Collection and called it like this:

{{staticUrl}}/api/users?page=2

So what's going wrong here? I would really appreciate if you share any idea about this with me...

Make sure you save your collection and then move to the actual request tab. I forgot to do the same and Postman cannot resolve the variable.

Also make sure not to press enter button after creating your variable name. It causes Postman to register carriage return symbol ⏎ and thus creates a key with an additional character.