Not able to stablish a connection to a repository

I am unable to connect to my Rational Team Concert server, which was used in the past but now it's impossible. Everything is configured correctly as it was before, with manual proxy settings for HTTP and HTTPS with a specific host, and SOCKS without any settings, all without authentication. For the location, I use the URL and name, and to connect to my server, it requires an intranet username and password. When I try to connect, another window pops up asking for the login and password information, and it keeps appearing in a loop. If I cancel the process, I get the following error:

com.ibm.team.repository.common.TeamRepositoryException: CRJAZ2384E Cannot connect to the repository at URL "https://eidesrtcp.svb.lacaixa.es/jazz", see the nested exception for more details.

    at com.ibm.team.repository.client.util.RepositoryUtil.getRepositoryId2(RepositoryUtil.java:137)

    at com.ibm.team.repository.client.internal.TeamRepositoryService.connectToAndUpdateTeamRepository(TeamRepositoryService.java:401)

    at com.ibm.team.repository.client.internal.TeamRepositoryService.getTeamRepositoryWithOverride(TeamRepositoryService.java:180)

    at com.ibm.team.process.rcp.ui.RepositoryCreationPage.createNewRepository(RepositoryCreationPage.java:233)

    at com.ibm.team.process.rcp.ui.RepositoryCreationPage.create(RepositoryCreationPage.java:200)

    at com.ibm.team.process.rcp.ui.RepositoryCreationPage$1.run(RepositoryCreationPage.java:129)

    at org.eclipse.jface.operation.ModalContext$ModalContextThread.run(ModalContext.java:121)

Caused by: java.io.IOException: Unable to tunnel through proxy. Proxy returns "HTTP/1.1 407 Proxy Authentication Required"

    at sun.net.www.protocol.http.HttpURLConnection.doTunneling(HttpURLConnection.java:1700)

    at com.ibm.net.ssl.www2.protocol.https.d.connect(d.java:18)

    at com.ibm.net.ssl.www2.protocol.https.b.connect(b.java:34)

    at com.ibm.team.repository.client.util.RepositoryUtil.getRepositoryId2(RepositoryUtil.java:115)

    ... 6 more

The handshake is done, because if I change the server configuration in the proxy, I receive a handshake error. So, what could be the problem? Any suggestions here?