CB Query field

I have one text field called country and one query field called VAT.
When entered a country name to the first field it will make a query to DB to check if it can be found with Ajax of CB Query plugin. Second one is VAT which makes a query to database to check the VAT value based on the country value.

I made a query in VAT field:
SELECT `a`.`vat` FROM `#__js_job_caw_country_vat` as `a`, `#__js_job_countries` as `b` WHERE `a`.`countryid` = `b`.`id` and `b`.`name` = `[cb_company_country]`

But substitution `[cb_company_country]` is not recognized and it gives an error.
Please give me a hint to solve it.

You need to use ' (single quotes) and you are currently using ` (accent) around your substitution.