can not access nfs

i have setting nfs as per manual but when i want access nfs from linux os ubuntu version 16.04 mounted there error access denied can i help if i mounted nfs on wd pr4100

If you have a WD Pro series unit then see the dedicated subforum for that device where people more familiar with that unit may be able to help. This subforum (My Cloud) is generally for the single bay/single drive My Cloud model.