so i need to make sure i understand what you have going on:
you want to show a record with it's associated subreport, listed one right after the other in the detail section of your report, right?
how long (height) is the detail section of your report in design view? if it is the full height of your paper it will go to the next page.
how long (height) is your subreport in design view? you can make it very short, and set its property CanGrow to YES.
another question--i don't understand your sentence in your last post "I don't know why it will seperate the records by the ID?" please explain.