I have negative cash flows (-19.71286, -19.84066, -19.97366, -20.11566, -20.28666, -20.48666, -20.69706, -20.94406, -21.22146, -21.53686, -20.97026, -20.97026, -20.97026,-20.97026, -20.97026, -20.97026, -20.97026, -20.97026, -20.97026, -20.97026) for 20 years in a project, these are all present values of the annual cash flows and initial investment is 66 MM USD. I want to calculate the profitability index. I calculate it like this:

```
CF$PV<- c(-19.71286, -19.84066, -19.97366, -20.11566, -20.28666, -20.48666, -20.69706, -20.94406, -21.22146, -21.53686, -20.97026, -20.97026, -20.97026,-20.97026, -20.97026, -20.97026, -20.97026, -20.97026, -20.97026, -20.97026)
profitability_index <- sum(CF$PV) / initial_investment (66)
profitability_index
```

I have 30 cases like this and for some cases, I get profitability index of -20, -8, -1.7 and figures like these. My supervisors say that this cannot happen as profitability index cannot be -20, the minimum it can be 0-1. I have calculated profitability index via excel in different ways (NPV/initial investment), but I still get numbers like -20/-8. Please what is the wrong thing I am doing here?