Precompilation error (ecpg)

Hi,
when trying to precompile the following code with
> ecpg -I/usr/include/pgsql ecpg_test.pc

I am getting the following error message

ecpg_test.pc:27: invalid datatype 'zipcode_record'

this is probably something very simple, but I don't get this error,
when processing the code with Oracle.
I would appreciate any feedback.
thanks
pawel

--------  ecpg_test.pc file  -------------
#include <stdio.h>
#include <string.h>

typedef struct {
  int zip;
} zipcode_record;

EXEC SQL INCLUDE sqlca;
void add_customer();

void main() {
/* just a test */
}

void add_customer() {
  EXEC SQL BEGIN DECLARE SECTION;
    zipcode_record  zrec;      /* line 27 */
  EXEC SQL END DECLARE SECTION;
}