strange behavior of mapconcat

[shortcutz]

Hi all,

In a piece of code I call mapconcat with these arguments:

(mapconcat 'org-no-properties "t" " ")

I'm getting the error (wrong-type-argument sequencep 115). This is the same
if I use the identity function or any other string instead of "t":

(mapconcat 'identity "t" " ")
(mapconcat 'identity "string1 string2" " ")

What am I doing wrong? I don't really understand where the 115 is coming
from. The code is unchanged after macroexpanding, and sequencep says
"string1 string2" and "t" are both valid sequences.

Thanks
R