define-markup-function problem

[Kieren MacMillan]

Hi all,

Could someone please explain why this works:

#(define-markup-command (test layout props stringA stringB) (string?  
string?)
        (interpret-markup layout props
        (markup #:bold stringA #:italic stringB)))

\markup \test #"one" #"two"

but this doesn't:

#(define-markup-command (test layout props stringA stringB) (string?  
string?)
        (interpret-markup layout props
        (markup #:column (cons stringA stringB))))

\markup \test #"one" #"two"

Thanks,
Kieren.