How can I add a negative number of days to a Custom Field date?

[Anders]

Hi 

I'm trying to add a negative number of days to a date.

I want to do "todays date + (-2wd)"

this is my rule :

, set custom field "Due" to "{triggercardduedate}", and set custom field "Due" to "{{%Due}+({{%DaysOffSet}}wd)}"

when I trigger the rule I get this:

I couldn't read a date in "{{%Due}+(-2wd)}"

Is it possible to ADD a negative number of days? I don't want to use subtraction since the same rule is used to add positive number of days as well