You can indeed paste in text. The problem is that Remoter only allows plain text. If the "text" you copied into the pasteboard has any formatting at all, then Remoter doesn't know how to handle it, and reports that error.
There is a ticket already in the system for this(
http://trac.remoterlabs.com/index.fcgi/ticket/371). I might be able to do something about it for the next version.
Thanks!,
Raf.