Packet Tracer cannot ping from across Linksys

Hi,

I have a Packet tracer network. I have 3 sub interfaces set up on a Main router, three VLANS set up on a switch. Wireless router has a standard set up with remote mgt enabled.

I can ping everything outside the wireless, I can ping everything inside the wireless, I can ping from inside the wireless to outside (i.e. i.e. PC4 to PC0) but I just cannot ping from outside wireless to inside, i.e. PC0 to PC4

Packet tracer PDU information states that the ICMP packet gets dropped by the wireless router, (The NAT table does not have a matched entry for this packet. It drops the packet!!!)

I have nothing done with NAT, do I need to set up NAT somewhere??

Any ideas greatly appreciated,
Thanks in advance...