I would check your print preview to make sure the pages you want are actually being included.
If they are then the next step would be to switch the print driver that you are using to a different flavor. Print drivers come in PCL5, PCL6 and PostScript. There are device specific print drivers and Universal Print Drivers (UPDs). Check out the software section of your printers support website to see what options are available to you.
A printer will print an entire print job before moving on. If your pages are missing then the printer is not recieving those pages for one reason or another.