I'll reply in english as it's the "universal" language for the KB.
We have a KB-Post that explains this message:
The Missing Import module basically tells you that an additional MIB required by the MIB that you're importing is not present in the folder of the MIB that you're importing. Essentially, if you open the MIB with a text editor you'll see something like this:
SOME-MIB-MIB DEFINITIONS ::= BEGIN
ifEntry, ifName, ifIndex
Counter32, Counter64, Gauge32, Unsigned32, Integer32, IpAddress,
MODULE-IDENTITY, NOTIFICATION-TYPE, OBJECT-TYPE, TimeTicks, OBJECT-IDENTITY
DisplayString, TEXTUAL-CONVENTION, AutonomousType, DateAndTime, PhysAddress
Basically, MIB's are inter-operable, which means that specific types that are defined in one MIB file can be imported in a different file. In your case, the rfc-1212.mib is missing. You may locate this MIB in the following path:
C:\Program Files (x86)\PRTG Network Monitor\MIB or on the internet.
Just make sure that this MIB is present in the same folder as the MIB from Trend Micro and then try importing it again.
Luciano Lingnau [Paessler Support]