how to sync google account with app market

[yeldarbs1]

i have an MID android tablet with an via vt 8650 arm 926 cpu running ver. 2.2 with 4gb flash memory. problem is i cannot download apps from app market be cause it says i have no device with this account, i check my accounts and sync settings and it gives my account name but says sync is turned off, but setting says sync automatic is turned on. some times if i make a new account i can slip an app in download but the next time i boot up i get the same thing,( no device found). is there another way toturn on sync for the account? and is it permanent each time i boot up? would rooting be worth the trouble? thank for any help.