Slice-timing correction error

Dear CONN experts, 

I downloaded the version of CONN  (20.b) in Linux, and performed functional analysis. I used the default preprocessing pipeline. 
I choose slice-timing: interleave phillips
When slice-timing correction started , an error ocurred: "item 'reference slice', field 'val': item must be an array of natural numbers."

I tried several times, and also choose: slice-timing interleave bottom-up and I also tried entering my own values, but the same error appears.

I would very much appreciate any help with this. 

thank you in advance,

Best regards, 

Carmen