In article <01bb89f1$bee01220$230260cf@mel>, mtalley@whts.com says...

>This flash works outstanding in automatic mode but when I switch it to TTL
>mode, I get the status light blinking on and off as if there was not enough
>light after I take a picture. I am shooting with an F3. This is not a new
>problem but after monitoring this newsgroup for a couple of weeks I thought
>I would ask. Anyone has any thoughts? Thanks for any comments. Please
>post to this group or email me at mtalley@whts.com

Either the ASA setting is higher than 400, or the shoe cover is not
rotated closed (necessary for the ASA "feeler" to engage the ASA tab
on the camera).
Hope This Helps