Backup database to backup device

CREATE PROCEDURE [dbo].[BackupDatabase]
        @dbname VARCHAR(50)
AS
BEGIN
        SET NOCOUNT ON;
        IF (ISNULL(@dbname, '') = '')
        BEGIN
            RAISERROR(N'Invalid parameter: @dbname cannot be NULL or empty string', 18, 0)
            RETURN
        END
        if   NOT (EXISTS (SELECT name FROM master.dbo.sysdatabases WHERE ('[' + name + ']' = @dbname OR name = @dbname)))
        BEGIN
            RAISERROR(N'Invalid parameter: database %D not found', 18, 0, @dbname)
            RETURN
        END
        BEGIN
                DECLARE @BackupDevice VARCHAR(256);
                Declare @backupsetName varchar(256);
                Declare @retaindays int=30;
                SET @BackupDevice = 'BACKUP DEVICE NAME';
                SET @backupsetName = lower(@dbname) + '_' + REPLACE(REPLACE(REPLACE(CONVERT(CHAR(16),CURRENT_TIMESTAMP, 120), '-', ''), ' ', ''), ':', '');
                Print 'Executing Backup database';
                Print '     Backup Device: ' + @BackupDevice;
                Print '     Backup set name: ' + @backupsetName;
                Print '     retain days: ' + cast( @retaindays as nvarchar(2));
                BACKUP DATABASE @dbname TO @BackupDevice with  RETAINDAYS=@retaindays, NAME=@backupsetName ;
        END
END
GO