it could be that you are echo()'ing the text in your include() file. and where you define the include() in your running file, it will execute everyting from the include() file then move ahead.
if you want to prevent this, then dont use echo() or print in your included file, but instead, if the value is in function then use return $result; where the text output is in $result. and then call the function name in your running file, which will then output the text in appropriate position.
hope i havent confused you even more..