I want to move my extreme further.. can I place a switch in that position and move it on with additional cable trough the switch. I tried and it doesn't seem to wot
If you are saying that the Airport Extreme works correctly when you originally extended the network using an Ethernet cable from your main router to the Airport Extreme.....then the AirPort Extreme will work correctly when you add an Ethernet switch and additional Ethernet cable......assuming that the switch is operating correctly and the Ethernet cable is operating correctly.
90%+ of problems like this can be traced to a bad port on an Ethernet switch, or a bad connection at either end of the Ethernet cable. Unfortunately, you cannot assume that a "new" Ethernet cable is a "good" Ethernet cable, nor can you assume that a switch is working correctly until it has been tested.
However, if you are saying that you originally set up the AirPort Extreme to connect back to your main AirPort router using a wireless connection......then you will need to reset the extending AirPort Extreme back to default settings and then configure it to extend using an Ethernet connection.
If you are still having problems, please provide more information.....things like
What device is acting as your "main" router
What operating system you are using on the Mac that you using to set things up
Screen shots of AirPort Utility, etc.