Cannot push to repository

I created a new repository "cvx++" and followed the "Importing existing files" instructions, but was unable to push:

$ hg push https://mihelich@bitbucket.org/mihelich/cvx++\\
pushing to https://mihelich@bitbucket.org/mihelich/cvx++\\
real URL is https://bitbucket.org/mihelich/cvx%2B%2B/\\
searching for changes
http authorization required
realm: Bitbucket.org HTTP
user: mihelich
password:
abort: authorization failed

I tried the same with another new repository named "cvxpp" and all is well, so I guess the '+' characters are a problem.