"Attempts count should be numeric!" - unable to change email text

hi, i've just enabled user disable 5.x-1.0 on my drupal 5.10 site.
i went to the user disable settings. There i've tried to change the text of the email wich will be sent to a user who blocked his account. I only used the variables used in the original english text. every time i press "save", the following message appears: "Attempts count should be numeric!"

i used 5 as number of times a user can try to enter the password and a time delay of 30 minutes. But that doesn't work.

So this way, it doesn't work. I then changed the words in my de.po language file. After that, i tried it out and entered 5 times the wrong password. After the fifth time i got a "internal server error". I think this might have happened because of the incorrect translation ("Attempts count should be numeric")

Can anyone help me please? because this would be a great module!!

thanks!