Having trouble building a compound IF formula

Book0.5 template.xlsx

I have been trying to create an IF formula to post the next lab draw date based on several criteria. I can get both halves to work correctly, but when I place then together it does not carry through the whole formula, it stops after the first two calculations either way I write it. I have an initial treatment, 30 days after the treatment I need blood work done, I also need blood work done 3 mths after treatment, and I need to follow the patient every 6 mths after that with blood work. Ideally, when I input the last blood draw it will post to either the 1 mth or 3 mth columns automatically depending if they have been done and these calculations performed so I can schedule things. But right now I will settle for this formula if anyone could help. Thanks.

I have: Col G (1 Mth draw) Col J (3 mth draw) Col L (Initial Tx) Col N (Last blood Draw) and Col O (Next blood draw and cell for the formula); I am working in row 4.

My formula is: IF(G4=0,L4+30,IF(G4>0,G4+60,IF(J4>G4,J4+180,IF(N4>J4,N$+180,J4+180))))

Any help would be appreciated

Sorry arlu1201, you are completely correct....

I ended up adding in the and function into my equation and after several hours realized that I had to make my arguments more relative to eachother. The AND fx worked great and the formula looked like this:

=IF(A4=0,"",IF(G4=0,L4+30,IF(AND(G4>0,J4=0),G4+60,IF(AND(J4>0,N4=0),J4+180,N4+180))))