| Right-click the package file, Properties |  |
| Go to "Digital Signatures", select the signature and click "Details" |  |
| Click on "View Certificate" |  |
| Click on "Install Certificate" |  |
| Select "Local Machine", click "Next |  |
| Select "Place all certificates on the following store", click "Browse" |  |
| Select "Trusted Root Certification Authorities", click "OK" |  |
| Click "Next" |  |
| Click "Finish" |  |
| The installation is complete |  |
| Close and re-open the package file properties, it should display as valid now |  |