Simple script with mangle

Hello. Pls help me with my problem
Did the simple script

:local commentName “Net”
:local i [/ip firewall mangle get value-name=disable number=[find comment=$commentName]];
:if (i=true) do={
/ip firewall mangle enable [/ip firewall mangle find comment=$commentName];
}

But it works only to enable
If i want to disable this rule change disable to enable and in last string enable to disable - but doesnt work
in what is the mistake?