How to assign "Date taken" data in a batch

[gvm]

Hello everybody!
Thanks a lot to XnView's developers for a very good product! I still use film camera and scan films. I got images with blank EXIF info in "Date taken" field. Anybody knows how to assign/change date in "Date taken" field for a batch of images? I can do it to each image separately but can't find how do it to a batch. Can't do it in Tools->Change Timestamp window too as checkbox "EXIF: Date taken" is inactive:

[xnview]

The picture has no "EXIF taken" field, i think?