substitution in layout-block

[Stefan Thomas]

Dear lilypond-users,
I tried to make a substitution in the layout-block, but without
success. I don't know what could be wrong.
Here is the short snippet:
\version "2.12.0"
keineTaktart = \layout { \context { \Staff   \remove
"Time_signature_engraver"} }
keineTaktzahl = \layout{ \context { \Score \remove
"Bar_number_engraver" } }
\relative {c4 d e f \break g1  }
\layout { \keineTaktart } \layout{ \keineTaktzahl }