On certain pages in my 40 page document, I am unable to set the number of columns by using Layout>Margins and Columns. The columns option is dimmed out. I have tried to set them on a blank page and pages where columns were previously set (I can see the guides). I am using a single Master for page numbering and it is applied to every page in the document. There are pages where I can set the columns. I've done some page comparison and can't find the setting that might control this. Using InDesign CS6 on Windows. Thank you.
Why are you not using multiple column text frames instead of 2 text frames with columns on the master page? This would give more flexiblity.