Iterating a multidimensional Lua Table in C

I have a problem iterating a multidimensional Lua table in C.

Let the Lua table be this i.e.:

local MyLuaTable = {
  {0x04, 0x0001, 0x0001, 0x84, 0x000000},
  {0x04, 0x0001, 0x0001, 0x84, 0x000010}
}

I tried to extend the C sample code:

 /* table is in the stack at index 't' */
 lua_pushnil(L);  /* first key */
 while (lua_next(L, t) != 0) {
   /* uses 'key' (at index -2) and 'value' (at index -1) */
   printf("%s - %s\n",
          lua_typename(L, lua_type(L, -2)),
          lua_typename(L, lua_type(L, -1)));
   /* removes 'value'; keeps 'key' for next iteration */
   lua_pop(L, 1);
 }

by the second dimension:

/* table is in the stack at index 't' */
lua_pushnil(L);  /* first key */ /* Iterating the first dimension */
while (lua_next(L, t) != 0)  
{
   /* uses 'key' (at index -2) and 'value' (at index -1) */
   printf("%s - %s\n",
          lua_typename(L, lua_type(L, -2)),
          lua_typename(L, lua_type(L, -1)));

   if(lua_istable(L, -1))
   {
      lua_pushnil(L);  /* first key */ /* Iterating the second dimension */
      while (lua_next(L, -2) != 0) /* table is in the stack at index -2 */
      {
         printf("%s - %s\n",
                lua_typename(L, lua_type(L, -2)),
                lua_typename(L, lua_type(L, -1)));
      }
      /* removes 'value'; keeps 'key' for next iteration */
      lua_pop(L, 1);
   }
   /* removes 'value'; keeps 'key' for next iteration */
   lua_pop(L, 1);
}

The output is:

"number - table" (from the first dimension)

"number - number" (from the second dimension)

"number - thread" (from the second dimension)

Afterwards my code crashes in the "while (lua_next(L, -2) != 0)"

Has anybody an idea how to correctly iterate the two dimensional Lua table?