C/C++ :: Using A Structure In Different Modules?

I'm trying to create a structure for a buffer that I can use in 2 different code modules. I've defined the structure in the main.h file

typedef struct
{
uint8_t frame[MRFI_MAX_FRAME_SIZE];
uint8_t rxMetrics[MRFI_RX_METRICS_SIZE];
} receiveBuffer_t; //SS; packetBuffer length is 24 Bytes, 20 for data packet, 1 for length, for rxMetrics, 1 for TxCount

Then set it up in main.c

static receiveBuffer_t XDATA receive_buf[8]; //SS; Store up to 16 received packets for debug

This works great in main but I want to also use this structure in another module. In other.c I've included main.h and am trying to use it as follows

extern receiveBuffer_t receive_buf[8]; // Receive buffer
for (i=0; i<PACKET_LENGTH+1; i++)
receive_buf[rec_head_ptr].frame[i] = mrfiIncomingPacket.frame[i];

I get the following error when I compile.

Error[e46]: Undefined external "receive_buf" referred in mrfi ( C:FlowTimerDebugObjmrfi.r51 )