key and signature problems (Ubuntu 12.04LTS)

Hello, since some day I have problems with the trinity repository. It started on June 30th with the following message: W: A error occurred during the signature verification. The repository is not updated and the previous index files will be used. GPG error: http://ppa.quickbuild.pearsoncomputing.net precise Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 96C95152F5CFC95C After updating the key with sudo apt-key adv --keyserver keyserver.quickbuild.pearsoncomputing.net --recv-keys 96C95152F5CFC95C Since that I get signature errors: W: GPG error: http://ppa.quickbuild.pearsoncomputing.net precise Release: The following signatures were invalid: BADSIG 96C95152F5CFC95C QuickBuild Trinity Desktop Environment W: A error occurred during the signature verification. The repository is not updated and the previous index files will be used. GPG error: http://ppa.quickbuild.pearsoncomputing.net precise Release: The following signatures were invalid: BADSIG 43F1DC4F2B8638D0 QuickBuild Trinity Desktop Environment Is there anything I can do to solve this issue? Thanks in advance. Stefan