Problem With Rtf Text box

I have a rtftextbox on the form and it is connected to a table inside the database. First time i enter some words into that text box. then i click a button (not relevant to rtftextbox.save, instead, adodc.recordset.update is used) to update the field in the table. Second time, when i try to edit or delete some words, and then update the database, it doesn't change anything but remains the same. The only thing i can do is to go to the database and delete those text from the data field inside the table. What's wrong with it?