Why can't I view my monthly or yearly org agenda?

Question

Issuing M-x org-agenda-month-vew and M-x org-agenda-year-view yields

Wrong type argument: number-or-marker-p, nil

Why am I getting this error?

Issuing M-x toggle-debug-on-error before the command yields

  calendar-gregorian-from-absolute(nil)
  org-agenda-compute-starting-span(nil month nil)
  org-agenda-change-time-span(month nil)
  org-agenda-month-view(nil)
  call-interactively(org-agenda-month-view record nil)
  command-execute(org-agenda-month-view record)
  execute-extended-command(nil "org-agenda-month-view")
  call-interactively(execute-extended-command nil nil)

Answer 1

The commands org-agenda-month-view and org-agenda-year-view are thought to be called from an agenda buffer AFAICS.

If you use the user interface of the agenda to call those functions this constraint is always fullfilled.

If you feel the need for a different behavior for those functions you could try to discuss this topic at the orgmode mailing list.