Thanks to your help!
Here is some lines of the MIB file.
SYMBOL-WS5000-MIB DEFINITIONS ::= BEGIN
IMPORTS
DisplayString
FROM RFC1213-MIB
OBJECT-GROUP, MODULE-COMPLIANCE, NOTIFICATION-GROUP
FROM SNMPv2-CONF
enterprises, TimeTicks, IpAddress, Integer32, Unsigned32,
Gauge32, Counter32, Counter64, BITS, OBJECT-TYPE,
MODULE-IDENTITY, OBJECT-IDENTITY, NOTIFICATION-TYPE
FROM SNMPv2-SMI
TEXTUAL-CONVENTION
FROM SNMPv2-TC;
.....
If I delete BITS character form the MIB file which is define IMPORT module,
then the compilation is well done.
Best Regards,
-Terry