he is making a valid point: the RFC states the command is "/topic <channelname> [topic]"
some clients have a /topic alias which will automatically do '/topic #current_active_channelname'. mIRC by default has this alias aswell (see script editor > aliasses).
if this does not work for you, than there could be several causes:
* the IRCd does not support the command, and isn't RFC compliant (which is a bad thing)
* you have a script which causes you to not see the server reply
* you have a script, overriding the /topic command with something else, causing it to never be (correctly) sent to the server
I think one of the 3 above options will be the case, and I actually put my money with the 2nd or 3rd option since I'm pretty sure for instance unrealIRDd does support this, as do most IRCd's I've ever worked with.
reason why the //echo version wouldn't work is if the topic starts with a number. use //echo -a instead.