CC2564MODA: Bluetopia "Stack Init Failed: -4."

Hi - I am trying to get the SPPDemo going on STM32F4's using NoOs. I have just connected up the boards at each end  for the first time to today & I'm running the same SPPDemo app at each end, modified only enough to allow for different ConsoleUart pins.

Both boards report:

OpenStack().

Stack Init Failed: -4.
Unable to open the stack.

So at least they are both running (;-))

The led in the loop beyond the MainThread() call starts flashing:

/* MainThread should run continously, if it exits an error occured. */
while(1)
{
ToggleLED(NULL); // Orange Led LD3 on Disc1 @ ~2Hz

BTPS_Delay(100);
}

So the MainThread has obviously exited.

I have set the jumpers as per SWRU417, appropriate to whether the Adaptor PCB's are on the Discovery board or Eval board, and made sure that I have the right module (XQFNEM or MODNEM) at the right end.

There is some mention of the Slow Clock in other earlier threads, but nothing about what to do with it in SWRU417.

Is there anything else that I might have not done? Needless to say, I was in a hurry to see it fire up & I haven't read the manual exhaustively yet!