When RTMP servers send data they sometimes send incorrect time stamps.
Jaksta will always record what it is given by the server.
If during playback this is incorrect then you can change it. Have you tried setting the time stamp to 15 using Jaksta's FLV Tool?
When you open the Jaksta's FLV Fix tool you need to expand the File Contents section at the bottom of the window. This allows you to reset the time stamps on all the Video and Audio parts of the file.
If that doesn't work during play back please upload the raw captured video via
http://www.jaksta.com/clientupload and email support AT jaksta.com so I can look at what else might be the problem.
Thanks
Craig