backup an SQL database using an ADO Query in Delphi 6

Here's what I'm trying to do: having a database on an SQL server I'm
trying to do weekly backups on a remote location. 1 file must be
created for each backup of the database.
The SQL query is:

declare @v1 char (24), @v2 char(4), @v char(30)
set @v1 = '\\Backup\Monitor backup\'
set @v2 = '.bak'
set @v = @v1 + :fileparam + @v2
backup database db_name to disk = @v

where fileparam is the name of the parameter defined in the
ADOQuery,and is defined as a string. The value is passed through the

parameters[0].value:= day; where day is a string of 2 characters;

The error I get is :'EOleException: Syntax error or access violation'.
I know it's because of the :fileparam in the set @v.... statement, but
I don't have any other idea how to parameterize the path. Does anybody
know how to solve this problem???