How can I fix my Central Locking - Chrysler Voyager CRD 2005?

My central locking has stopped working. I have been taking out the I.O.D. fuse and waiting about 20 seconds then replacing it, putting the key in the ignition and turning it to the ON position, without starting the car. The indicators would flash twice and then the central locking would start working again. I tried this a couple of times today, but that isn't working anymore. Checked the fuse and it is ok. Any ideas?