Some MIBS are dependent on others so when you run into those issues you have to look in the mib and find all its dependencies for instance generally near the top of the mib you find these IMPORT statments generally the standard and RFC MIBS are included in the netxms mibs folder.
*Note this mib only imports from RFC which should be fine and not give an error
IMPORTS
enterprises, OBJECT-TYPE, NetworkAddress, IpAddress,
Counter, Gauge, TimeTicks
FROM RFC1155-SMI
ifIndex, ipAdEntAddr, ipRouteDest, tcpConnLocalAddress,
tcpConnLocalPort, tcpConnRemAddress, tcpConnRemPort
FROM RFC1213-MIB;
*Note this mib imports from a standard mib as well but also from another vendor mib RUGGEDCOM-MIB so if i did not include the RUGGEDCOM-MIB in the folder i would recieve the error of not being able to resolve
IMPORTS
MODULE-IDENTITY, OBJECT-IDENTITY,
OBJECT-TYPE, Integer32 FROM SNMPv2-SMI
TEXTUAL-CONVENTION, TruthValue,
DisplayString FROM SNMPv2-TC
OBJECT-GROUP FROM SNMPv2-CONF
ruggedcomMgmt FROM RUGGEDCOM-MIB;
also post the mibs your are trying to import and i can see if i get the same issues