@EnyGmaTiK:
As the A600 powersupply only can supply 3A on the 5V rail, make sure to try without harddrive, extra diskdrive etc connected to get as much power as possible available for the accelerator.
(edit): Btw, the port is not designed to give any clicking sound when inserting the accelerator. The connector is of the type used for example in PCI-bus connectors which you can find on a normal PC-motherboard. Maybe if you insert it extremely fast it will make a sound when the circuitboard part on the A1200 motherboard hits the bottom of the connector on the accelerator, but thats about it.
/Patrik