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/xxx/Downloads/NotarizedApp/AppNotaryAndDistrib.app' 

which gives following o/p

/Users/xxx/Downloads/NotarizedApp/AppNotaryAndDistrib.app: valid on disk
/Users/xxx/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/xxx/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/xxx/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/xxx/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 xxx.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...