How to limit a Custom Field in Trello to accept incremental values only

[Carlos Almeida]

Hi there, Sorry for the newbi question.

I have just created a numeric custom field and I was wondering if there is a way I could limit value insertion to be incremental only (e.g. if the existing value is X it will only accept new values greater than X).

I tried Butler but it doesn't seem to accept custom field variables for the Trigger side:

TRIGGER---

when custom field

MYFIELD

is set to a number lower than {customfieldvaluebefore}

ACTION ---

set custom field

MYFIELD

to {customfieldvaluebefore}

Am I doing something wrong in butler or do I need to use something else? Is there is a simple way I can programe this without having to spend a week learning intricate programming languages?

Thanks : )

Carlos 

[Carlos Almeida]

Apparently Butler can't parse is set to a number lower than {variable}. It does work with is set to {variable} though. Anyone has a sugestion?