Hi,
Have a look here.
SnapDrive cannot mount a LUN:
https://library.netapp.com/ecmdocs/ECMP1135147/html/GUID-D7B5A793-150B-4913-937C-3B628986BAF4.html
If the steps in the link does not help, then:
1) Login to the server where SD is installed : Check event logs.
2) Try to mount the lun manually using SD.
It it not resolved, let us know with SD version and event logs.