Bad engine ID value after -e flag

Hi,
 
I'm currently testing the SNMP v3 traps (net-snmp 5.2.1.2 for RH).and I
encounter the error "Bad engine ID value after -e flag" when my agent
starts.
 
Here are the details:
 
snmpd.conf
-----------------
trapsess "-e 0x0102030405 -v 3 -u myuser -a MD5 -A my_password -l
authNoPriv" localhost
 
# SNMPv3 user
rwuser myuser
 
 
myuser was created as follow:
net-snmp-config --create-snmpv3-user -a "my_password" myuser
 
 
snmptrapd.conf
----------------------
createUser -e 0x0102030405 myuser MD5 my_password DES my_password
 
 
Using this configuration I'm able to send snmpv3 traps with snmptrap:
snmptrap -e0x0102030405 -v3 -umyuser -aMD5 -Amy_password -lauthNoPriv
localhost 42 coldStart.0
 
.and the traps are correctly intercepted by snmptrapd.
 
However this is just for test. What I need to do is to send traps from
my agent using send_v2trap API.
But when the agent starts up it parses the snmpd.conf and I get that
error.
 
I've tried also the oldEngineID from /var/net-snmp/snmptrapd.conf (even
that this match is only required for inform) and the result is the same.
 
In snmpcmd man page the -e EngineId is optional but if I remove that
switch from snmpd.conf I receive another error message:
Invalid version specified after -v flag:  3 -u myuser -a MD5 -A
my_password -l authNoPriv
 
 
Could someone help me with this?
 
 
Thanks a lot!
Eugen