What wrong with this irule

Could someone tell me what wrong with code below?

 

 

if { NODE:[LB::server]) eq "172.16.1.15"} {

 

TTP::redirect "http://www.test.com/signon.htm"

 

}

 

 

I got the error:

 

 

01070151:3: Rule [new_rule] error:

 

line 5: [parse error: PARSE syntax 232 {syntax error in expression " NODE:[LB::server]) eq "172.16.1.15"": variable references require preceding $}] [{ NODE:[LB::server]) eq "172.16.1.15"}]

 

 

 

Thanks,