I have LRT4 with LR6. my visual deficker button works on one batch of photos and not another. The only difference I see between the 2 batches is the lens used. specifically it will not work with my Canon but will work with my Bower. I can not believe that the lens would make a difference. I have (I believe) followed the tutorials on both. Any help appreciated. thanks

What do you mean with "is not working" - are the visual previews not being generated? Maybe you could just provide some information that would enable me to help you. Screenshots would be nice, the logfile might be of help as well.

This post was last modified: 2015-05-02, 12:38 by Red Shift.

    By "not Working" I mean the button is not active. See attachment. That is nothing happens when clicked on with curser. Unfortunately I do not know where to find the log file.    
Just added a full size attachment

It seems like if the visual previews have not been generated for the whole sequence. Just go though the sequence and check for the "Visual Lum" column in the table. The column must have values everywhere. If not, just select the photo that does not have a preview and see, if it gets generated.
If everything fails you can regenerate all previews with "shift f5". Sometimes single images are corrupt and LRT cannot create the Visual Previews for them. If one single VP is missing, the deflicker won't be available.

Success! 2 images in the sequence were missing the "Visual Lum". Note though that I had to remove the files from the sequence. I tried both the selection of the individual photo and the "shift f5" advice, neither worked. Once removed I could proceed with the deflicker. "Garbage in Garbage out" rule applies here I suppose. Also, once in a while in LRT3 after rendering via LR4 some images for the timelapse "failed" as reported by LR3, I am assuming this is the same issue.
Thanks for the help

Yes, if images are corrupt, rendering will probably fail as well.