whatsapp back up restore problem from icloud

[iffi123]

first i made a backup of whatsapp chat history to icloud from whatsapp messenger then to verify it i went to icloud manage storage in iphone and i can see there was back up of whatsapp chat history size 40 mb so then i restored ios from itunes and install whatsapp again then when restore window came up in whatsapp, it said back up not found in icloud so i could not restore that back up, allthough i again went to icloud manage storage in phone, and there is still whatsapp back up.
why whatsapp is not showing my backup from icloud ? wifi net is working fine.

any help or suggestion to get back my back up would be highly appreciated. what should i do now ?

Thanks million