As per page 1189 of the 12.5 admin guide  mentions particular target types .

DLP versions :- 11.x , 12.x , 14.x

Step 1 :- created an access database  in MS Access

Step 2:-  Created  a network share and  placed the file in it 

Step 3:-  Created a keyword policy 

Step 4:-   Created a  file system target scan for MS access

Mentioned the shared path as highlighted below 

Entered  the Credentials  for the Shared path 

Step 5:-  Created incidents