tcpdump and route domain and LDAP

I am configuring a virtual server with a LDAP profile/configuration. During the testing we tried to use tcpdump to capture all the traffic to the LDAP server, it did not capture anything. I then configured a pool with LDAP server on port 389 I could capture all the monitoring traffic. Not sure why. We do have multiple route domains on the LTM but with tcpdump I tried -nni 0.0 and also tried capture all the traffic in the VLAN via /routedomina/VLAN still could not capture any LDAP traffic to my server or even just traffic on port 389. I even tried capture while doing a ldapsearch, nothing was captured either.

So questions, have I done anything wrong? Or is that a bug or something? We use LTM 11.2.0 HF1.

Thanks in advance