The details that are likely to help questions to be answered on the org mailing list.
(print emacs-version)
(print org-version)
(print (pp-to-string org-babel-default-header-args))
(print (pp-to-string org-babel-default-header-args:R))
=
Eg:
"24.3.1"
"8.2.10"
"((:eval . \"always\") (:padline . \"yes\") (:noweb . \"no-export\") (:exports . \"both\") (:results . \"output replace\") (:comments . \"noweb\") (:session . \"none\") (:cache . \"no\") (:hlines . \"no\") (:tangle . \"no\")) "
"((:session . \"*R*\")) "