Alec Harley reported an interesting (read: annoying) behavior around the use of Dateparts inside date-related functions used by Report Builder

In older builds, it appears you may not use the nice abbreviated Dateparts that we're used to (for example "dd" instead of "Day"). If you do, Report Builder throws the following unhandled exception:

"Operation is not valid due to the current state of the object."

After digging around I found that right now we must use the un-abbreviated Datepart, AND it must be capitalized correctly or we'll see the error:

DateAdd("mm", 3, SomeDateField) // Will blow up with the message above

DateAdd("Month", 3, SomeDateField) // Will work!

DateAdd("month", 3, SomeDateField) // Explodes with the same error message