So i am making an erp program for practice from adventureworks2019 database in management studio in sql and one stored procedure with output parameters didnt run properly unless i specified their value as null, while others similar procedures did not have such an issue. Why? and are the other procedures faulty? What is the textbook way syntactically executing procedures with output parameters?, also any tips pls?

drop procedure if exists sohead;

create procedure sohead
@BusinessEntityid int,
@customerid int,
@persontype nchar(2) output,
@storeid int output,
@orderdate datetime output,
@duedate datetime output,
@accountnumber nvarchar(15) output,
@salespersonid int output,
@territoryid int output,
@billToAddressid int output,
@shipToAddressid int output,
@shipMethodid int,
@creditcardid int output,
@currencyrateid int =null,
@subtotal money,
@taxamt money,
@freight money,
–totaldue self generated and computed
@comment nvarchar(128)

AS
BEGIN
set nocount on;
begin try

        begin transaction
        --@storeid
        
            select @storeid = storeid from sales.customer where CustomerID = @customerid;

        --orderdate 
        SET @orderdate = GETDATE();

        --duedate
        SET @duedate = DATEADD(day, 15, @orderdate);


        --salespersonid
        
        if @storeid IS NULL
            SET @salespersonid = NULL;
        else
            SELECT @salespersonid = SalesPersonID 
            FROM Sales.Store 
            WHERE BusinessEntityID = @storeid;


        --territoryid
        select @territoryid = territoryid from sales.Customer
        where customerid = @customerid;

        --biiltoaddress  AND  shipaddressid
        --;WITH persontypecte AS (
        --      SELECT persontype 
        --      FROM person.Person
        --      WHERE BusinessEntityID = @businessentityid
        --  )
        --select @persontype = persontype from persontypecte
        select @persontype = persontype FROM person.Person
                WHERE BusinessEntityID = @businessentityid;

        if @persontype = 'SC' 
        BEGIN
                    ;with billshipadd as(
                        SELECT AddressID FROM  
                        person.BusinessEntityAddress

                        where BusinessEntityid = @storeid

                    )
                    select   @BILLTOADDRESSID = addressid,@SHIPTOADDRESSID = addressid  from billshipadd; --address GIA 'SC'
        
        END
        ELSE IF @PERSONTYPE = 'IN' 
        BEGIN
                    ;with billshipadd as(
                        SELECT AddressID FROM  
                        person.BusinessEntityAddress

                        where BusinessEntityid = @businessentityid

                    )
                    select   @BILLTOADDRESSID = addressid,@SHIPTOADDRESSID = addressid  from billshipadd; --address gia 'IN'
        END;             

        --creditcardid

        select @creditcardid =  CreditCardID from Sales.PersonCreditCard where businessentityid = @BusinessEntityid;

        --accountnumber 

        select @accountnumber = accountnumber from sales.customer where customerid = @customerid;

        --currencyrateid

        --null

        


        


        insert into sales.salesorderheader(revisionNumber, orderdate, duedate, shipdate, status,
        onlineorderflag, purchaseordernumber, accountnumber, customerid, salespersonid, territoryid,        
billtoaddressid, shiptoaddressid, shipmethodid, creditcardid, creditcardapprovalcode,       
currencyrateid, subtotal, taxamt, freight, comment, rowguid, modifieddate)
        VALUES(
        0,
        @orderdate,
        @duedate,
        null,
        1,
        0,
        null,
        @accountnumber,
        @customerid,
        @salespersonid,
        @territoryid,
        @billToAddressid,
        @shipToAddressid,
        @shipMethodid,
        @creditcardid,
        null, --credit card approval code
        @currencyrateid,
        @subtotal,
        @taxamt,
        @freight,
        --@totaldue, --mono toy
        @comment,
        newid(),
        getdate()
);

        commit transaction
    end try
    begin catch 
        SELECT
            ERROR_NUMBER() AS ErrorNumber,
            ERROR_SEVERITY() AS ErrorSeverity,
            ERROR_STATE() AS ErrorState,
            ERROR_MESSAGE() AS ErrorMessage;

    IF @@TRANCOUNT > 0
        rollback transaction;
        throw;
    end catch

end;

exec sohead @businessentityid=1983 , @customerid=30113 ,@shipmethodid= 1, @subtotal =5,
@taxamt =5, @freight = 5, @comment = null,@persontype = null, @storeid = null,@orderdate = null, @duedate = null, @accountnumber= null, @salespersonid= null,
@territoryid = null, @billToAddressid = null, @shipToAddressid=null, @creditcardid = null;

Apparrently this is the right way to execute it
but i thought this was enough : exec sohead @businessentityid=1983 , @customerid=30113 ,@shipmethodid= 1, @subtotal =5,
@taxamt =5, @freight = 5;