expression cannot be used as an assignment target in SAP HANA stored procedure

Hi ,

I created sample stored procedure using scalar variables . In the stored procedure I am using INOUT parameter . Please find the below stored procedure.

drop procedure scalar_proc;

create procedure scalar_proc(IN OUT a bigint) LANGUAGE SQLSCRIPT AS

BEGIN

    ins_msg_proc('a before ' || :a);

    a := a + 1;

    ins_msg_proc('a after ' || :a);

END;

drop procedure inout_proc;

create procedure inout_proc(IN x bigint) LANGUAGE SQLSCRIPT AS

BEGIN

    init_proc();

    ins_msg_proc('x before ' || :x);

    call scalar_proc(:x);

    ins_msg_proc('x after ' || :x);

END;

But when I am creating the inout_proc it is throwing error like  "expression cannot be used as an assignment target: :X" .

Please help me how to resolve this issue.

Thanks & Regards,

Ramana.