Do I Need Repeaters Instead Of Second Switch

I have radio link where i work. Connections have been made to other pcs with an 8 port switch. from that switch i have extended another wire which is nearly 90 mts. that connection iss again connected to several pcs and working fine. But i have again extended another wire of about 90 mts from the 2nd switch. All other connections are working fine on the second switch but there is no light on the switch for the extended one.. Where have i gone wrong? Do i need to place repeaters instead of the second switch??