cannot subscript something of type <data variable, no debug info>

["Daniel Miller \(IMI\)" <dan at imi-test dot com>]

I'm trying to debug an application with gdb... I have a struct that is
declared thus:

typedef struct S_Module_s
{
  unsigned powered_up;
       ...  other data elements  ...
} __attribute__ ((__packed__)) S_Module;

extern S_Module Mod[1];

I tried compiling both with -g and -ggdb, with no change in the symptoms.

I don't seem to be able to display any of the contents of Mod[0], at all....
I get effects such as:

(gdb) p Mod[0]
cannot subscript something of type `<data variable, no debug info>'
(gdb) p (S_Module) Mod[0]
No symbol "S_Module" in current context.
(gdb) p (struct S_Module_s) Mod[0]
No struct type named S_Module_s.

What do I have to do to get gdb to recognize my variables??  Virtually every
GUI-based debugger out there is a wrapper around gdb, to if it's not happy,
nobody's happy!!!  Please help!!

    Dan Miller