I've got the same problem, mine was caused though by having a Clifford Alarm fitted...
When it went wrong and I had to have it removed, the indicator lights no longer flash when locking/unlocking...
Been to the stealers I said I think it's a wiring problem they had the car for a few hours they reactivated it on the computer but it kept rejecting it. They then agreed yes it's a wiring problem then "done me over" for £100!
We need the car for further checks - I haven't bothered they seem pretty clueless unless it's something straight forward...