Sharing data in a 32-bit dll

I have converted a 16-bit dll to 32-bit. The old dll had been written to allow data to be shared between processes. I have modified the shared data to fit inside a #pragma data_seg("shared") section. However I have a question about how this works. If I write the code like:

typedef struct mesg_type
{
  UINT num_msg;
  char mesg[MAX_LENGTH];
} mesg_type_item;

#pragma data_seg("shared")
  mesg_type_item shared_list[MAX_ITEMS];
#pragma data_seg ()

the data does not become shared. But if I do this:

#pragma data_seg("shared")
  mesg_type_item shared_list[MAX_ITEMS] = {0,""};
#pragma data_seg ()

It appears to work fine.

Any explanations?