Mysql stored procedure parameters do not seem to work with "@" (character "B")

I am changing the MS SQL database to MySQL.

I rewrote one of the stored procedures that takes a parameter with a name @Account_Number. When I run a stored procedure in MySQL, I get the following message: Error Code: 1048 Column 'Account_Number' cannot be null.

Using the workbench, I finally got busy and realized that when I deleted the "@" from my stored procedures and renamed them, the parmAccount_Numberstored procedure would be executed.

I really want the input parameters of the stored procedures to be the same, and I don't want to go back and rename the MS SQL parameters ... just in case I want to flip the flop funds.

I can not find information on what MySQL does with the "@" ....

Is there any way to make it work with "@"?

EDIT

Declared Stored Procedure

CREATE PROCEDURE `My_sp`(
 `@Account_Number` varchar(8),....)

insert sp part

insert into 
My_Table
(
    Account_Number, ...
)
values
(
    @Account_Number,...
)