SharePoint Calculated field forumla

Question

=IF(([ATP Type] = "Tin", DATE(YEAR([First Production Date]), MONTH([First Production Date] + 4), DAY(First Production Date))),
(IF([ATP Type] = "Film & Tray", DATE(YEAR([First Production Date]), MONTH([First Production Date] + 3), DAY(First Production Date))), 
DATE(YEAR([First Production Date]), MONTH([First Production Date] + 1), DAY(First Production Date))))

Above is what I have come up with for the following requirement but it's not quite right.

I have a drop down with three string values. Each string value has a numeric value in months that I wish to use to calculate a new date field. There is a target production date field which is being used to create the new calculated column as a ref marker.

I need the above formula to meet my requirement. Could anyone please assist?

Thanks

Answer 1

=IF([WIP Target First Production Date]="","",IF([ATP Type]="Tin",DATE(YEAR([WIP Target First Production Date]),MONTH([WIP Target First Production Date])-4,DAY([WIP Target First Production Date])),IF([ATP Type]="Film & Tray",DATE(YEAR([WIP Target First Production Date]),MONTH([WIP Target First Production Date])-3,DAY([WIP Target First Production Date])),IF([ATP Type]="Case",DATE(YEAR([WIP Target First Production Date]),MONTH([WIP Target First Production Date])-1,DAY([WIP Target First Production Date]))))))

This was my solution in the end.