Use parameter that contains a current date formula at the data source

Question

I get extraction files from the database in . csv format with default:

C://director_staff/CSV_01-01-2019/file.csv

A new folder is created every day, so to automate this in power BI, in the orgiem of the data I made the command below:

= Csv.Document(File.Contents(pCaminho & DateTime.ToText(DateTime.LocalNow(), "dd-MM-yyyy") & "\2_areas_tematicas.csv"),[Delimiter="#(tab)", Columns=6, Encoding=65001, QuoteStyle=QuoteStyle.None])

I would like to put this whole date command in a parameter, just like I did with the directory footpath, but he won’t accept:

Anyone who can help, I’d be most grateful.