Dynamic Dates with Task Lists

Hello,

Currently my company is not using MS Project, however I am looking at using SharePoint Online's Task list to help me achieve the same kind of functionality. In doing so I have run into a snag with trying to calculate dynamic start and end dates.

Current Columns with type:

Title (Single line text)

Predecessors (look up)

Start Date (date field)

Man Days (number field)

Due Date (date field)

What I would like to do:

For the start date:

If (Title has Predecessor)

{

Start Date = {Predecessor}[End Date]

}

else

{

Select Start Date

}

For the End Date

End Date = [Start Date] + [Man Days]

The issue I am running into, is that every try I try to put in an equation in the end date it tells me that the equation is not valid.

Any ideas would be very helpful.

Thanks,

- Manish