Couldn't create a cpp component project — build unsuccessful with error “_remove_ref() couldn't resolved”

I am using Centos6.10 and REDHAWK2.1.2/2.2.1 installed from RPMs. It works fine to create a cpp component without any in/out ports. However, when I add one input and one output port to the project (test_cpp), I have the following error no matter what data types are assigned to the ports:

Method '_remove_ref' could not be resolved.

in test_cpp_base.cpp:

test_cpp_base::~test_cpp_base()
{
    dataFloat_in->_remove_ref();
    dataFloat_in = 0;
    dataFloat_out->_remove_ref();
    dataFloat_out = 0;
}

It turns out that nowhere in the code system has declared / defined method "_remove_ref()".

Besides, I have also checked the installed dependencies and got the following output in the terminal:

[owner@localhost ~]$ rpm -qa | grep omni
omniORBpy-libs-3.6-4.el6.x86_64
omniORBpy-debuginfo-3.6-4.el6.x86_64
omniORB-doc-4.1.6-2.el6.x86_64
libomniEvents2-2.8.1-1.el6.x86_64
omniEvents-utils-2.8.1-1.el6.x86_64
omniORBpy-devel-3.6-4.el6.noarch
omniORB-devel-4.1.6-2.el6.x86_64
omniEvents-server-2.8.1-1.el6.x86_64
omniEvents-bootscripts-2.8.1-1.el6.x86_64
omniEvents-doc-2.8.1-1.el6.x86_64
omniORB-4.1.6-2.el6.x86_64
omniORB-servers-4.1.6-2.el6.x86_64
omniEvents-debuginfo-2.8.1-1.el6.x86_64
omniORB-utils-4.1.6-2.el6.x86_64
libomniEvents2-devel-2.8.1-1.el6.x86_64
python-omniORB-3.6-4.el6.noarch

[owner@localhost ~]$ ldconfig -p | grep libomni
libomnithread.so.3 (libc6,x86-64) => /usr/lib64/libomnithread.so.3
libomnithread.so (libc6,x86-64) => /usr/lib64/libomnithread.so
libomnisslTP4.so.1 (libc6,x86-64) => /usr/lib64/libomnisslTP4.so.1
libomnisslTP4.so (libc6,x86-64) => /usr/lib64/libomnisslTP4.so
libomnijni.so.0 (libc6,x86-64) =>    
/usr/local/redhawk/core/lib64/libomnijni.so.0
libomnijni.so (libc6,x86-64) =>     
/usr/local/redhawk/core/lib64/libomnijni.so
libomniORB4.so.1 (libc6,x86-64) => /usr/lib64/libomniORB4.so.1
libomniORB4.so (libc6,x86-64) => /usr/lib64/libomniORB4.so
libomniEvents.so.2 (libc6,x86-64) => /usr/lib64/libomniEvents.so.2
libomniEvents.so (libc6,x86-64) => /usr/lib64/libomniEvents.so
libomniDynamic4.so.1 (libc6,x86-64) => /usr/lib64/libomniDynamic4.so.1
libomniDynamic4.so (libc6,x86-64) => /usr/lib64/libomniDynamic4.so
libomniConnectionMgmt4.so.1 (libc6,x86-64) =>     
/usr/lib64/libomniConnectionMgmt4.so.1
libomniConnectionMgmt4.so (libc6,x86-64) =>     
/usr/lib64/libomniConnectionMgmt4.so
libomniCodeSets4.so.1 (libc6,x86-64) => 
/usr/lib64/libomniCodeSets4.so.1
libomniCodeSets4.so (libc6,x86-64) => /usr/lib64/libomniCodeSets4.so

[owner@localhost ~]$ rpm -qa | grep omniORB-devel
omniORB-devel-4.1.6-2.el6.x86_64

Any suggestions on fixing this building error would be appreciated!

P.S. This problem can be classified into the category "What is an undefined reference/unresolved external symbol error and how do I fix it". However, the solution is not just to add this method manually to the code system. Instead, it might be a missing "include" file, etc. Whoever is familiar with REDHAWK sdr, please help. Thank you.