Can't ping wireless laptop from internal network
Your router most likely has two separate networks -- one for wired and the other wireless. You can check the subnet mask as Alberto suggests, but if this was the case then your device would probably have the same default-gateway assuming you are using DHCP.
- The router may be configured to firewall the two networks from one another.
- Another cause of this behavior may be that the laptop has its own firewall enabled. Do you have another wireless device you can test with?