According to https://answers.launchpad.net/launchpad/+question/266806:
Launchpad won't generate a signing key for your PPA until you've
uploaded a source package to it. Many users create PPAs without ever
uploading anything, so we avoid cluttering the keyservers until we
know the key will actually be used.
Looking at the build details for your PPA at https://launchpad.net/~unixinfo/+archive/ubuntu/openshell/+builds?build_text=&build_state=all, I noticed that none of your builds succeeded. Therefore, there is no signing key for your PPA because I suspect that you need at least 1 successful build.
P.S.: I am assuming that "uploading a source package" means successfully building your package. If this is wrong, please let me know. In any case, having no successful builds also makes the PPA fairly pointless :).