Calling C++ from within ADA

[CVANOVER@bamanet.ua.edu]

Is there a way to call a C++ procedure from within ADA? I can call a C 
procedure with 

package C_LIB is
        procedure clear_screen;
        procedure sleep_a_moment;
private
        pragma interface(c,clear_screen);
        pragma interface(c,sleep_a_moment);
end C_LIB;

However, when I compile the same C procedure in C++ I get the following error:
0706-317 ERROR: Unresolved or undefined symbols detected:
                 Symbols in error (followed by references) are
                 dumped to the load map.
                 The -bloadmap:<filename> option will create a load map.
.clear_screen

I've tried adding INTERFACE_INFORMATION but it doesn't seem to help.  

I am using IBM AIX on an RS6000.

Thank you
Chris Vanover
The University of Alabama
CVanover@bamanet.ua.edu