Referring to this thread:
http://www.zabbix.com/forum/showthread.php?p=71466#post71466
and this solved call:
https://support.zabbix.com/browse/ZBX-2452

Some oid have hexadecimal values with spaces. this is solved in the call mentionen above.
Zabbix defaults to recalcutate to the numeric system. But some OID's out there needs to be recalculated to a string.
(example) This website uses the right calculation http://www.string-functions.com/hex-string.aspx
It comes to the following example:
OID value is = 32 38 C2 B0 43 2F 38 32 C2 B0 46
Remove spaces and calculate to string = 28°C/82°F