Script-fu contactsheet.scm raises "Error: eval: unbound variable: gimp-image-get-selected-layers"

Hi,

I am new to using .scm files and scripts through the GIMP in general.. but would like to make use of the contactsheet.scm script. This error is given when running the script through Filter > Combine > Contact Sheet.. and when running the script through the console. Any special considerations to using this script successfully?

I have been trying this with the stable release, version 2.10.32 and Development 2.99.14 - both give the same error message.

Cheers, Tim