Can one of you expert excell gurus please help me with the following.

I am trying to put the retirement staking plan on excell. I have as a primary target $600 (divsor 6 thus min bet $100) I have this in col C. In colD I have my losses. This is from col M which is the profit and loss col. Thus my formula in col D is =-M4. ColE is the total of colC +ColD formula =C5+C5. At present this offsets all profit and losses in colM into my total target instead of the desired stop when previous losses are recouped.

My formula for col D should in fact be =-M4 if <0 use 0. How I can I effect this I've played with it for hours and I concede defeat The computor has been saved two inches from the floor several times.

I thank you in advance
Regards Beton