Cannot select a frame when rotating a page to landscape

I have some tables that are too wide to put in portrait mode, so I am inserting a horizontal master page to cope with this. I have looked up a tutorial and it takes me through the steps to rotate the page clock wise, then it says to delete the existing frame so I can insert a new one that will have the text flowing in the correct direction.

My problem is I can't select this text frame. I have no idea why. In the tutorial I am watching she does this effotlessly. I don't even get the indicators (little black boxes), that I indicates that I can select it.

Do any of you have any ideas why I can't select this? I've checked that my document isn't locked (the padlock button next to the printer).