Backup Sql query

[C# Programming]

HI.. This is my backup query.. its not workin
Pls send me wat's the error in this query and how to get backup database..

alter PROCEDURE [dbo].[sp_BackupDatabase]
@databasename varchar(32),
@path varchar(256),
@filename varchar(64)AS
set nocount on
declare @sql varchar(4000)
select @sql ='BACKUP DATABASE ' + ltrim(rtrim( @databasename ))
select @sql = @sql +'TO DISK = ''' + ltrim(rtrim(@path)) + ltrim(rtrim(@filename)) + ''' '
select @sql = @sql +'WITH INIT'
print @sql
execute ( @sql )
select 'Database successfully backed up!' [Result]