Could be several things.
1 You didn't bleed the brakes correctly and air got into the system at the master cylinder. You'll need to re-bleed them. Make sure the master cylinder stays filled with fluid at all times while bleeding, if it isn't, you'll be sucking air into the system.
2 ABS pump has air in it. Dealer can cycle the ABS module with a scan tool to get the air out. If it's in the ABS pump, it will be hard for you to do at home.