Perl script to display All BigIP pool members

in the continuity of my script, I still have the error :

SOAP-ENV:Client Unknown method "{urn:iControl:System:Failover}:get_failover_state"

I think it's comming from :

 
 sub SOAP::Deserializer::typecast 
 { 
 my ($self, $value, $name, $attrs, $children, $type) = @_; 
 my $retval = undef; 
 if ( (defined $type) && ("{urn:iControl}LocalLB.MonitorStatus" eq $type) ) 
 { 
 $retval = $value; 
 } 
 if ( (defined $type) && ("{urn:iControl:System:Failover}FailoverState" eq $type) ) 
 { 
 $retval = $value; 
 } 
 return $retval; 
 }

I'm not sure how to modify the {urn:iControl:System:Failover}FailoverState in order to kill the error ...

any idea ?

tal