How to make that extension is exported in .xpi without it getting damaged?

My problem is that:

I already loaded my extension in Firefox, passed its damage verification test and was able to sign it, but when I downloaded the .xpi to install it manually. But when trying to manually install the Firefox extension it throws an alert message indicating that the extension is damaged.

I find no fault in my extension because when testing experimentally everything works.

I need your urgent support. I am new to creating extensions in Firefox and its Developer Forum. Thank you

Please email amo-admins AT mozilla DOT com with the details.