Hey guys.  this dead air was a problem i always had until someone told me to use markers. The advice i was given that the last marker will automatically tell the software that this is where the song ends.  I've inserted markers but i still have this dead air.  One of the tips above was to highlight the song length using the time ruler. I've done this but when i click on File > Export I get an  error saying "The specified selection does not contain any audio data".  Should the last marker till the song to stop playing?  And if not, is there a way around that error i'm getting about the specified area not containing any audio data.   Thanks guys

Markers by themselves do not designate end of song. SONAR exports until there is no more data unless a time-based selection is made. First select the tracks to export, then select the area between the markers to export. Make sure when exporting audio based on MIDI data the appropriate audio or instrument tracks are part of the selection too or you will receive the "The specified selection does not contain any audio data" error.

There is a menu item to place and end of project instruction. It's not a marker per se.

Thanks for the replies guys.  I'll try both suggestions. I'll do a search for that "end of project" menu item.