Not possible to set a variable at a test case

I have a test case with an action ‘Set Text’ and a text object. I have also created a variable at the tab Variables but when I try to connect the variable to the test input the variable is nog recognized. I double click on the input field of the test cases. I select Value Type Variable and when I open the dropdownbox for the available Variables, its empty.

How can I solve this problem. I use version 3.8.6, saved the project, closed Katalon and restarted but still not possible to use the generated variable.

Try changing your test case view from MANUAL view to SCRIPT view and then within your test case, on the line that you are trying to set the text, type WebUI.setText()

Now click inside these brackets and start to type the name of your recently created variable and it should auto-populate.

Also, try checking the contents of the .TC file which relates to your test case as that will show you if the variable for the test case has been saved.