I'm currently configuring a pair of Zabbix servers on v1.8.4 and am having problems with polling F5 virtual server stats, I think its to do with the length of the oid as the pollers for Cisco and Junipers work fine.
An example oid for inbound bytes:
.1.3.6.1.4.1.3375.2.2.10.2.3.1.7.25.97.112.105.46. 109.117.115.105.99.46.111.118.105.46.99.111.109.95 .50.55.56.56.95.118.115...