Two vendor certifications for netscaler pointing to the same OID was the problem. The item number 1 the number 2.
1. NetscalerVserverServiceCAMib (snmp-netscaler-vserver-service.xml) showed only metric 'ServiceWeight'
2. NetscalerVserverServicesHealthCAMib (snmp-netscaler-vserver-services-health.xml) has 3 metrics regarding Service Health
By disabling the item 1 via snmpcollector Raw Configure under VendorCertifications an performing a device rediscover the problem is resolved.