Because rough-milled lumber comes in random widths and lengths, it is not possible to generate cutting diagrams for it. CutList Plus does not know what widths and lengths you have available.
If you want layout diagrams for your rough-milled lumber, just treat it as dimensioned lumber instead. You can then enter the exact sizes of all your rough lumber stock, specify how many of each size you have, and get layout diagrams for them.
(This works with CutList Plus fx Silver Edition and higher.)