[PD-dev] Symbol not found: ?

[nosehair911 at bellsouth.net]

I am trying to get a external written using functions outside of Pd.  I have my header files included and 
the external is compiling but when I try to load it into Pd I get this error:

10): Symbol not found: _whatever-external-function
Expected in: dynamic lookup
[import]: ERROR: can't load library in FTIR_CXX

What can I do to fix this?
Alain