Thank you for your post.
Without seeing your file, it is difficult to determine if the script is damaged. If you think this dialog box is functioning improperly, try creating a new script with only that dialog box. Then, from your main script, replace the dialog box script step with "Perform Script" that calls the new script. If that works, then try incorporating that step back into the main script.
...a simple dialog box that features a field...
wich type the input field is ?
what do you want to enter into it ?
when you press OK, come on an alert ?