Stapling is not working for a package installer and hence user receives "Apple cannot check it for malicious software."

I created a new sample project and enabled hardened runtime. The code signing is successful and app successfully got uploaded to apple notary service as I received a xcode notification regarding notarized app export.

I have validated the code signing using below command

codesign -vvv --deep --strict '/Users/***/Downloads/NotarizedApp/AppNotaryAndDistrib.app' 

which gives following o/p

/Users/***/Downloads/NotarizedApp/AppNotaryAndDistrib.app: valid on disk
/Users/***/Downloads/NotarizedApp/AppNotaryAndDistrib.app: satisfies its Designated Requirement

My requirement is to distribute the appliation software through a package installer, for the same I created a installer package using package tool [http://s.sudre.free.fr/Software/Packages/about.html]. The codesigning of installer package is also successful

productsign --sign "Developer ID Installer: Team Name (Team Identifier)" "AppNotaryAndDistri.pkg" "AppNotaryAndDistri_1.0_Installer.pkg"

The O/P of productsign command is mentioned below:

productsign: using timestamp authority for signature
productsign: signing product with identity "Developer ID Installer: Team Name (Team Identifier)" from keychain /Users/***/Library/Keychains/login.keychain-db
productsign: adding certificate "Developer ID Certification Authority"
productsign: adding certificate "Apple Root CA"
productsign: Wrote signed product archive to AppNotaryAndDistri_1.0_Installer.pkg

To notarize the signed installer package, i used the following command

xcrun altool --notarize-app --primary-bundle-id "application-bundle-id" --username "apple-account-id" --password "app-specific-password" --file AppNotaryAndDistri_1.0_Installer.pkg

which returns a request uuid successfully

No errors uploading 'AppNotaryAndDistri_1.0_Installer.pkg'.
RequestUUID = 7f24e166-b47a-47d8-b09d-21268886351e

The notarization info command o/p is below:

RequestUUID: 7f24e166-b47a-47d8-b09d-21268886351e
    Status: success
  Status Code: 0
Status Message: Package Approved

Till now everything looks good and no error from apple, also developer_log doesn't give any error. But when i try stapling using

xcrun stapler staple 'AppNotaryAndDistri_1.0_Installer.pkg'

it gives following error

Could not validate ticket for /Users/***/Downloads/MacSigning/AppNotaryAndDistri/AppNotaryAndDistri_1.0_Installer.pkg

The staple and validate action failed! Error 65.

Tried below command

xcrun stapler staple -v 'AppNotaryAndDistri_1.0_Installer.pkg'

which says

Downloaded ticket has been stored at file:/// path-to-ticket
Could not validate ticket for /Users/***/Downloads/MacSigning/AppNotaryAndDistri/AppNotaryAndDistri_1.0_Installer.pkg
The staple and validate action failed! Error 65.

The problem is without stapling, When user tries to install the software, the system prompts an alert saying ***.pkg can't be opened because Apple cannot check it for malicious software. I don't want user should see such alerts. I am stuck on it from a week. please let me know what is wrong in the process, did i miss any step? Pls assist...