Default Sales Order Request Date field to two weeks after document date based on conditions

Hello, team - I’m trying to create a customization for one of our branches.  They would like all new Sales Orders of Type = “QT” to have the Requested On date be the OrderDate + 14.  This would only be relevant to Branch 05 in our system. 

I’ve attempted to put a formula in the Requested Date Default field.  I’m aware that this doesn’t identify any branch conditions, but figured I’d give it a try anyway.

=[OrderDate]+IIf( [OrderType]='QT', 14, 0)

However, this only resulted in an error, so my guess is that it’s the wrong way of going about it.  Any thoughts?  Thanks!