Variables don't work Mysql

I'm trying to use variables in my query but when I write it the variable configuration lateral menu doesn't appear.

The query is:

SELECT * FROM transacciones_mensuales [[where tran_code={{codigo}}]]

This just happens when I use Mysql because when I write the same thing, but my source is an Oracle database, Metabase recognizes my variable.

If I run the query the next error is displayed:

unknown escape sequence {{codigo}}

I'm using v0.34.2

Could you help, please?

Hi @marhabed
Please post “Diagnostic Info” from Admin > Troubleshooting.
And check your browser console for any errors, when you’re in the Native/SQL editor page.