Problem deleting dates with exiftool

[TopShoeter]

Hi,
I am having a problem deleting dates with exiftool. I downloaded exiftool-12.93_64.zip and extracted it to d:\utils and renamed exiftool(-k).exe to exiftool.exe. It seems to have been installed correctly as I can display an image's metadata just fine but attempting to remove the creation date just gives me this result. 

D:\Utils\exiftool>exiftool -DateTimeOriginal= d:\temp\image.jpg
    0 image files updated
    1 image files unchanged

What am I missing?
Thank you.

[Phil Harvey]

This will happen if the file doesn't contain a writable DateTimeOriginal tag.

Did you see DateTimeOriginal in the -s output when extracting information?

- Phil

[TopShoeter]

Thanks Phil, that was the problem. I tried with another file and -alldates= and DateCreated and it came back with 1 image files updated but when I looked at the properties in windows explorer I still see the created and modified dates. Edit: This, I now realize is the file creation date and not date taken. But if I load the image into on1 photo raw I do still see the creation (taken) date.
thanks,
Gerry.

Edit2: exiftool seems to work as intended and the problem is probably with ON1. I will investigate further.
Sorry for any inconvenience caused.
Gerry.