I would start by writing a PL/SQL test harness for the procedure rather than using SQL*Plus bind variables. Write a small PL/SQL block of the form:

declare
v_vis_c_fname emps.c_fname%TYPE;
v_vis_c_lname emps.c_lname%TYPE;
...
begin
load_names_p.pr_load_names (v_vis_c_fname, v_vis_c_lname, [more variables listed here]...);
end;

Get that working, then selectively replace each variable with its bind equivalent until you can track down the problem. Also, make sure you are not inadvertantly using two different user IDs - e.g. you could be compiling the package under one ID but running it under a different one (which has its own version of the package).