Planner-list predecessors for fixed date tasks

[pete davidson <caitifty gmail com>]

Hi all

Apologies for what's probably a newbie question. 

I'm trying to use Planner to manage academic grant applications.  As such, there's a number of key tasks whose dates are externally set and non-negotiable (such as the date the grant must be submitted to the funding agency, or the date a letter of intent is due to the funding agency).  I've been 'locking' these dates by creating a milestone task (eg "Submit grant") with a schedule of 'on fixed date' on the required date.  

The problem I'm having is when I try and link these milestone tasks to the rest of the tasks in the project by setting a predecessor.  This produces the error "You cannot add a relationship to a task with a Must Start On constraint."  I've also tried using a one-day task instead of a milestone task, but get the same error.

Is there another approach to dealing with externally set fixed dates that I'm missing, or a way to set milestone tasks which allows linking to other tasks?

Any suggestions would be most welcome.

Regards

Pete