why is here dobry but not dobrego?
personel is not animated.(as can be seen by macie dobry pesonel, nie macie dobrego personelu) Do not ask why. I do not know.
does that mean i use dobrego when i need genitiv with negation?
yes, dobrego is genitive masculine, and accusative for masculine animated.
Hmm - an English speaker needs to go through the English sentences!