do a 'show mod csm X tech proc 4'

LB Rjct: rule not match 0

LB Rjct: no real 4843 (2)

LB Rjct: acl denied 0

LB Rjct: no cfg policy 109

LB Rjct: svr init denied 0

LB Rjct: invalid rlid 0

LB Rjct: VIP max-conn 0

LB Rjct: L7 ver mismatched 0

LB Rjct: L7 max parse len 0

LB Rjct: L7 SSL format 0

LB Rjct: L7 parser 0

LB Rjct: no rslt buffer 0

LB Rjct: no lkup buffer 0

LB Rjct: no cookie buffer 0

LB Rjct: no cl NAT port 4087329 (42334)

At the same time, you should also probably get a sniffer trace of csm portchannel.

So you can track a failure.

Gilles.