Visio: Acrobat PDFMaker 'Retain some Layers in the selected page' greyed out

[DB1982]

I am trying to export a visio file with layers to pdf, using the Adobe add-in in Visio I have 3 options to export:

1. Flatten all layers

2. Retain all layers

3. Retain some layers in the selected page

1 and 2 are selectable but 3 is greyed out and I can't figure out why