SRVE0255E: A WebGroup/Virtual Host to handle /ktnb has not been defined

dear all   i had Pool KTNB with 4 member : 192.168.85.139:9081, 192.168.85.139:9082, 192.168.85.140:9081, 192.168.85.140:9082 run IBM Websphere 7. I had created HTTP Virtual Server KTNB 10.64.80.7...