Can't upload artifacts to the staging repo

I am trying to push some artifacts of swagger-socket project ( https://github.com/swagger-api/swagger-socket) to the staging repo.

mvn release:prepare went fine.

However, the uploading step with mvn release:perform
ended with the following error:

[INFO] — maven-install-plugin:2.3.1:install (default-install) @ swaggersocket-project —
[INFO] Installing /Users/d025803/repos/github/swagger-api/swagger-socket/release/target/checkout/pom.xml to /Users/d025803/maven/repos/com/wordnik/swaggersocket-project/2.0.0-RC1/swaggersocket-project-2.0.0-RC1.pom
[INFO] Installing /Users/d025803/repos/github/swagger-api/swagger-socket/release/target/checkout/target/swaggersocket-project-2.0.0-RC1.pom.asc to /Users/d025803/maven/repos/com/wordnik/swaggersocket-project/2.0.0-RC1/swaggersocket-project-2.0.0-RC1.pom.asc
[INFO]
[INFO] — maven-deploy-plugin:2.7:deploy (default-deploy) @ swaggersocket-project —
Uploading: http://oss.sonatype.org/service/local/staging/deploy/maven2/com/wordnik/swaggersocket-project/2.0.0-RC1/swaggersocket-project-2.0.0-RC1.pom
[INFO] ------------------------------------------------------------------------
[INFO] Reactor Summary:
[INFO]
[INFO] swaggersocket-project ............................. FAILURE [15.834s]
[INFO] swaggersocket-protocol ............................ SKIPPED
[INFO] swaggersocket-server .............................. SKIPPED
[INFO] swaggersocket-scala-client ........................ SKIPPED
[INFO] swagger-integration ............................... SKIPPED
[INFO] swaggersocket.js .................................. SKIPPED
[INFO] swaggersocket-echo ................................ SKIPPED
[INFO] swaggersocket-wordnik ............................. SKIPPED
[INFO] swaggersocket-twitter ............................. SKIPPED
[INFO] swaggersocket-helloword ........................... SKIPPED
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 16.637s
[INFO] Finished at: Fri Dec 19 16:48:10 CET 2014
[INFO] Final Memory: 13M/158M
[INFO] ------------------------------------------------------------------------
[ERROR] Failed to execute goal org.apache.maven.plugins:maven-deploy-plugin:2.7:deploy (default-deploy) on project swaggersocket-project: Failed to deploy artifacts: Could not transfer artifact com.wordnik:swaggersocket-project:pom:2.0.0-RC1 from/to sonatype-nexus-staging (http://oss.sonatype.org/service/local/staging/deploy/maven2): Failed to transfer file: http://oss.sonatype.org/service/local/staging/deploy/maven2/com/wordnik/swaggersocket-project/2.0.0-RC1/swaggersocket-project-2.0.0-RC1.pom. Return code is: 301, ReasonPhrase:Moved Permanently. -> [Help 1]
[ERROR]
[ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch.
[ERROR] Re-run Maven using the -X switch to enable full debug logging.
[ERROR]
[ERROR] For more information about the errors and possible solutions, please read the following articles:
[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/MojoExecutionException
[INFO] ------------------------------------------------------------------------
[INFO] Reactor Summary:
[INFO]
[INFO] swaggersocket-project ............................. FAILURE [23.575s]
[INFO] swaggersocket-protocol ............................ SKIPPED
[INFO] swaggersocket-server .............................. SKIPPED
[INFO] swaggersocket-scala-client ........................ SKIPPED
[INFO] swagger-integration ............................... SKIPPED
[INFO] swaggersocket.js .................................. SKIPPED
[INFO] swaggersocket-echo ................................ SKIPPED
[INFO] swaggersocket-wordnik ............................. SKIPPED
[INFO] swaggersocket-twitter ............................. SKIPPED
[INFO] swaggersocket-helloword ........................... SKIPPED
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 24.617s
[INFO] Finished at: Fri Dec 19 16:48:10 CET 2014
[INFO] Final Memory: 8M/123M
[INFO] ------------------------------------------------------------------------
[ERROR] Failed to execute goal org.apache.maven.plugins:maven-release-plugin:2.1:perform (default-cli) on project swaggersocket-project: Maven execution failed, exit code: '1' -> [Help 1]
[ERROR]
[ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch.
[ERROR] Re-run Maven using the -X switch to enable full debug logging.
[ERROR]
[ERROR] For more information about the errors and possible solutions, please read the following articles:
[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/MojoExecutionException

This URL http://oss.sonatype.org/service/local/staging/deploy/maven2
returns the error message with text:

"Staging of Repository within profile ID='7edbe315063867' is not yet started!"

When I manually try to upload a bundle.jar, I get this error as well
Artifact upload failed.
User 'ay' missing 'stage' permission for staging profile: 19dca794a64ec1

Could you help me in resolving this issue?

regards, aki