please check whether the options 'Show link to original images?' and 'Show link to original images for guests?' in tab 'Detail View' -> 'General Settings' of the configuration manager are enabled.
Thank you very much that solve the problem. It will be easy if instead of
Do you want to display a link to the original image? Choosing this option will display a link to the original image underneath the detail view of the image. This reference is displayed only in case the original image is larger than the detail image.
Also would add.
This will display Original image on a Pop up slimbox when detail image its click.
will solve some confuse on other people like me. LOL