Conditional statement in CRM Word template based on field value

I am having a problem with word templates.

First I created CRM document template and then I added required fields from XML Mapping Pane as Content Controls (plain text).

Then I created a rule inside a word template to only show field if it contains a value, and if it is empty to hide it

{ IF <<field_name>> <>"" <<field_name>> }

This is working just fine.

Now I want to create a new conditional rule inside a word template which is based on field value – if a CRM field value is equal to 24 months then write text 24 months, else write text unlimited.

{IF <<duration>> = ”24 months” “24 months” “unlimited”}

I don’t know if there is some syntax problem with my conditional statement, but this isn’t working. I have also tried to solve this using bookmark method (https://crmtipoftheday.com/716/conditional-values-in-word-templates/), but that didn’t help either.

Does anyone have an idea how to solve this?