Dynamic Memory Alloc for struct in struct

I am trying to do dynamic memory allocation for a structure which contains arrays of structures.  I keep getting an 'assignment type mismatch' error when I try to compile the code.

Basically I'm trying to store data for a number of tests performed at a number of different sites.  If I can get this simpler code to work I will add other layers of structs to hold the data points and test conditions.

Here is the code so far:

#include <stdio.h>
main()
{
  int i, j, sz, NO_OF_SITES, NO_OF_TESTS;
  struct testStruct {
    int i_test;
    int j_test;
  };
  struct siteStruct {
    int i_site;
    int j_site;
    int k_site;
    float x_site;
    float y_site;
    struct testStruct *test;
  };

  struct siteStruct *site;
  struct testStruct *p_test;

  /* I read these values from a file so I
     don't know them at compile time */
  NO_OF_SITES = 3;
  NO_OF_TESTS = 5;

  sz = NO_OF_SITES * sizeof (struct siteStruct);
  site = (struct siteStruct *) malloc (sz);
  for (j=0; j<NO_OF_SITES; j++) {
    for (i=0; i<NO_OF_TESTS; i++) {
      sz = sizeof (struct testStruct);
      p_test = (struct testStruct *) malloc (sz);
      site[j].test[i] = p_test;
    }
  }
}

I get the error on this line:

      site[j].test[i] = p_test;

I get the same error with this code:

      site[j]->test[i] = p_test;

The compiler tells me that the thing on the left is a structure.  How do I make it look like a pointer to a structure?

What am I doing wrong?  Thanks.