i use sonar 8.5 and i use korg pa600qt keyboard i know how to sync with sonar as midi sync...
but i need to sync in middle of project???when i try he start from start???
how can i do that??  tnx

Hi and welcome to the forums.
Can you explain in a little more detail what you mean by synch ?

sync mean connecting  my korg keyboard pa600qt to my computer by USB cable (look like the printer one) and using sonar 8.5 in my computer to recording(midi)
so i make sonar slave(midi sync) and when i start any rhythm or style in the keyboard the sonar start to record my playing (midi)
ok...know i make a mistake in the middle of song(midi)and need to replace it...or
i need to start syncing the record in the middle of song

You will have to disable slave mode and use sonar like a normal DAW.
What you want to do is set up punch in recording parts. this way you can press play and listen, then play and record will happen automatically.

tnx 4 reply ...but i need to continue in midi sync  
or...i need to start (midi)syncing and (midi)recording at measure no. 16  by start the keyboard's style
i make it with a more complicated idea ...i start recording as normal(no sync) (midi tracks) then in time i need  i start recording then at 16 measure i start playing style but its need more effort to correct the late
((((sorry for my bad English)))  

It is up to the device sending MIDI sync (your Korg) to send a "song position pointer" message to the slave (Sonar). Have a deep look in the Korg manual. (I see this in the manual: "In Sequencer mode, if you set a Locate Measure other than 1, the Song Position will go back to that measure.") The idea is to tell the Korg where to start playing.

I READ THE MANUAL AND FOUND THAT  (SONG POSITION)....TALKING ABOUT THE KEYBOARD'S INTERNAL SEQUENCER 
I NEED TO START RECORDING(MIDI) IN(SONAR) IN (SYNC MODE) (AND SONAR IS SLAVE) AT MEASURE NO. 20 BY PRESSING  START IN THE KEYBOARD...IF I DO SO HE START FROM FIRST MEASURE????ANY HELP

Check the System Common section of the MIDI Implementation Chart in your user manual to determine if Song Position is transmitted.  I found the manual for the PA600 on the internet, but not the QT.  The PA600 does not transmit or receive Song Position, which means that you can't sync to the middle of a song.  That is a limitation of your KORG hardware, not SONAR.
 
IMHO, your best option is to use Record Punch in/Punch out in SONAR as Chuck suggested.
Set the start and end of the Punch section to the location you want to replace.  Start recording from the start of the song with the KORG synced to SONAR.  SONAR will only replace the section of the song that you defined in the Punch in/Punch out range.
 
EDIT:  Removed help section documentation link, since I just realized the OP is using SONAR 8.5 and my link was for the current SONAR version.
 
Hope this helps,
-- Ron

It looks like the PA600 and PA600QT share the same manual, downloadable here http://www.korg.com/us/support/download/manual/0/305/1945/
 
It says in the MIDI spec near the end that they do not send or recognise song position pointers, so Sonar can not be synced to the Korg's song position and the Korg can not be synced to Sonar or any other DAW's transmitted song position.
 
So some other way of achieving the desired result will be necessary.