(VS2005)
hi, i'm new at snmp api and i was trying to buid a simple Snmp manager wich only makes a Get operation
all it's ok at startup, creating session and the others handles (pdu, source entity, destiny entity and context)...
then i send the message and retreives it...well, i must do it...
i was thinking a lot but don't understand why a memory access violation ocurrs when calling the SnmpRecvMsg...i was following examples to keep secure of right steps..but something is not ok..

theese are the handles:

HSNMP_PDU hPdu;
HSNMP_ENTITY hDest;char DestIP[]=""; //there i put dest ip
HSNMP_ENTITY hSrc;char SrcIP[]=""; //same thing with my ip
HSNMP_CONTEXT hContext;char Ctx[]="public";
HSNMP_VBL hVbl;
smiOCTETS dContext;
smiOID dName;
smiVALUE dValue;

...defining...

hDest = SnmpStrToEntity(hSession,DestIP);
if (hDest!=SNMPAPI_FAILURE){AfxMessageBox(CString("Destination resolved!"));}else{AfxMessageBox(CString("Destination can not be resolved\n"));}
//////////////////////////////////////
hSrc = SnmpStrToEntity(hSession,SrcIP);
if (hSrc!=SNMPAPI_FAILURE){AfxMessageBox(CString("Source resolved!"));}else{AfxMessageBox(CString("Source can not be resolved\n"));}
//////////////////////////////////////
dContext.ptr=(smiLPBYTE)Ctx;
dContext.len=strlen(Ctx);
hContext=SnmpStrToContext(hSession,&dContext);
if (hSrc!=SNMPAPI_FAILURE){AfxMessageBox(CString("Context resolved!"));}else{AfxMessageBox(CString("Context can not be resolved\n"));}
//////////////////////////////////////
dName.ptr = OID;
dName.len = sizeof(OID)/sizeof(smiUINT32);
dValue.syntax = SNMP_SYNTAX_NULL;
dValue.value.uNumber = 0;
hVbl = SnmpCreateVbl(hSession,&dName,&dValue);
//////////////////////////////////////
hPdu = SnmpCreatePdu(hSession,SNMP_PDU_GET,NULL,NULL,NULL,hVbl);
if (hPdu!=SNMPAPI_FAILURE){AfxMessageBox(CString("PDU Successfuly created!"));}else{AfxMessageBox(CString("error creating PDU"));}

after checking all values it's ok, send the message...
when i retrieve this:...

Recvi = ::SnmpRecvMsg(hSession,&hSrc,&hDest,&hContext,&hPdu);

..aplication crashes...references types are ok...so..
why produces a memory access violation ?? (reading)
can u help me?