C++ Builder, static linking, Tag4Info and unresolved externals

I am using Codebase v6.x with BCB 6. We are statically linking
C4LIB.LIB.

I can successfully use classes Code4, Data4, Index4 and Tag4, but
whenever I try to use Tag4info I get unresolved external errors from
the linker. I have been getting by using TAG4INFO structs instead, but
now I need to be able to generate an index tag definition dynamically.

The code is:
#include "d4all.hpp"

    Code4 t_codeBase;

    t_codeBase.accessMode = OPEN4DENY_RW;
    try {
        Data4    t_data;
        Index4   t_index;
        Tag4info t_tagInfo(t_codeBase);

        t_data.open(t_codeBase, "MY_TABLE.DBF");
        if (t_data.isValid())
        {
            try {
                // will add to Tag4info here, then

                t_index.create(t_data, t_tagInfo);

            } __finally {
                t_data.close();
            }
        }
    } __finally {
        t_codeBase.initUndo();
    }

The errors are:
[Linker Error]Unresolved external 'Tag4info::~Tag4info() referenced
from...
[Linker Error]Unresolved external 'Tag4info::Tag4info(Code4&)
referenced from...

Can anybody offer suggestions about what I am leaving out?

Thanks for your help.

Kathleen