"No Such Instance currently exists at this OID" retuned even the OID is correct

"No Such Instance currently exists at this OID" retuned even the OID is correct like nsCPUusage OID: 1.3.6.1.4.1.5951.4.1.1.41.6.1.2 sysHealthDiskPerusage OID: 1.3.6.1.4.1.5951.4.1.1.41.8.1.5 etc...