associate extended data

[Angelo2449]

from where to all,
with this code:

        (command "_text" centrotxt 0.50 0 nomeelemento "")
        (setq nomeentita (entlast))
        (setq oldlist (entget nomeentita))
        (setq thedata (list -3 (list "" (cons 1000 nomeelemento) (cons 1000 (rtos suplorda)))))
        (setq newlist (append oldlist (list thedata)))
        (entmod newlist)

I don't think it works, can someone of good will help me?
Thank you.