The JSON format is very picky about having exact syntax. Every comma,colon and quote has to be exactly right or cgminer miner cannot use it.
Here is an example from one of my rigs:
"pools" : [
{
"url" : "http://gld.cryptocoinmine.com:3333",
"user" : "xxxxxx",
"pass" : "xxxxxx"
}
]
,
"intensity" : "15",
"vectors" : "2",
"worksize" : "256",
"kernel" : "scrypt",
"lookup-gap" : "2",
"thread-concurrency" : "0",
"shaders" : "1564",
"gpu-engine" : "900",
"gpu-fan" : "0-75",
"gpu-memclock" : "1350",
"gpu-memdiff" : "0,0",
"gpu-powertune" : "0,0",
"gpu-vddc" : "0.000",
"temp-cutoff" : "95",
"temp-overheat" : "85",
"temp-target" : "75",
"api-port" : "4028",
"expiry" : "120",
"gpu-dyninterval" : "7",
"gpu-platform" : "0",
"gpu-threads" : "1",
"hotplug" : "5",
"log" : "5",
"no-pool-disable" : true,
"queue" : "1",
"scan-time" : "60",
"scrypt" : true,
"temp-hysteresis" : "3",
"shares" : "0",
"kernel-path" : "/usr/local/bin"
}
true and false in this JSON format is different in that it does use quotes when used as a parameter. Make sure the comma is after the true parameter and that there is no comma after the last parameter.