Butler - Moving due date forward by variable number

[MaciekSarnowicz]

I have created a Trello board to keep track of regular maintenance tasks. Each task has its own repeat cycle which is stored in "Weeks Interval" custom field. For example, for a task to be done once a year, that field value will be 52. 

Now, I created a Buttler Card Button that will, among other things, advance the due date to the next maintenance due. I am using a simple action like this:

set due in {{%Weeks Interval}} weeks

but I am getting an error. If I replace the custom field with a hard-coded number (say 5), this works. 

I've read the help post on date arithmetic and custom variables in Butler, but cannot figure it out. I am just starting with Butler, and I am sure I am missing something simple here. 

Regards,

Maciek 

[MaciekSarnowicz]

I was able to get this working if I use a different variable that does not have space in the name. I created a variable called 'wks' and if I use it, the expression above works as expected.