Reading data from a RadioButton

People managed to save the data of a radiobutton inside the firebase but I am not able to read.
In the screen below I created three conditions: Male, Female and Others, and assign the value to them as M, F, O.

To perform the update I first perform a search for the registered CPF and bring the data for each field.
Buscar CPF

created a variable called update. And on the Update button I follow the same layout as the save button.

The error that is arising is: The operation Checked cannot accept the arguments:, [M]
Note: You will not see another error reported for 5 seconds.

How to solve this?

use Do it to debug your blocks. see also tip 4 here App Inventor: How to Learn | Pura Vida Apps