what mistake i made?

during my duty at davao regional hospital pediatric department under the supervision of lyra mae jaranilla r.n, on july 28-30, this year, i charted my sample charting to my patient chart, once we are ready to go home the one staff said that the ball pen i used is not totally green because my shift is 3 pm to 11pm. but is blue green.. if you really watch my work its not really blue green it's somethiong green that is not totally green yet the other staff thier also using those kind of ballpen i used... i was scolded by our c.i becuase of that, does i make mistake? or if i made mistake then, is it grave? that we all in the group are scolded?.. i myself agree that i made mistake in using that ball pen but i dont know it is not usable in that institution... i am being blamed by my teacher an even with my groupmate... i feel so tired hearing there sentiments about what happen.. and i feel so low in self esteem.. i dont want to duty again with same teacher because of that situation...
while im in my room, i really figure out why i am gravely blame?.... maybe next time i put blog i can asnwer this question!! for now bye.bye...