problem with changing a password to ibutton1977

i am writing and reading to ibutton1977 (from dallas) ..and it is being done ok.
if i try to write the same password again and again to the ibutton it is being done ok..

but when i try to write a diffrent password to the ibutton (from the first password ) i get error..
so i cant change passwords to my ibutton 1977...

what is the reason for that ?
does anybody know ?


now i am stuck with that ..

thanks.