This version is incompatible with the 6.1 version of Drupal core

I am not sure, but I think the .info file is generated in an old way, it should be like this :
; $Id: json_server.info,v 1.2 2008/01/13 15:48:11 dmitrig01 Exp $
-name = Javascript Server
-description = Provides an JSON server.
-package = Services - servers
-dependencies = services
-core = 6.x
\ No newline at end of file
+name = "Javascript Server"
+description = "Provides an JSON server."
+package = "Services - servers"
+dependencies[] = services
+core = 6.x

(example from http://drupal.org/files/issues/json_server_info_2.patch)
thanks :-)