<b> ldapsearch error </b>

I think that you're just using the wrong variable. You have:

set IP [concat “Octeto_Uno.$Octeto_Dos.$Octeto_Tres.1”]
if {$IP != ""}{
if { [matchclass $LoginIP equals $::LDAP_GroupA]}{
pool PoolA
} elseif { [matchclass $LoginIP equals $::LDAP_GroupB]}{
pool PoolA
}
} else {
pool $::defaultPool
}
TCP::release
}

You're constructing the ip address in the "IP" variable, but then you're using the original "LoginIP" variable in the matchclass statements.

Also, if you're concerned that you might get input that isn't an IP address, you should do some data validation to make sure that the "Octeto" variables actually contain numbers.