IMB T-40 will not connect wireless network sitting next to Linksys 2.4 Ghz router. Router works with two other?

IMB T-40 will not connect wireless network sitting next to Linksys 2.4 Ghz router. Router works with two other lap tops. IBM finds the network but will not connect. I check everything I know to check. It uses Cisco Systems PCI Sireless Lan Adapter. Tools keep telling me to make sure the eternet cable is connected. The connect screen also says waiting for the ociation. How do I fix this?