globalChannelMap not working

globalChannelMap.get("counter0");

if (counter0 == undefined)

{

var counter0 = parseInt(FileUtil.read('//export//netapp2//dept//IT//Mirth-Test//counter//good.txt'));



}

var counter0 = parseInt(counter0);

var counter0 = counter0 + 1;

globalChannelMap.put("counter0", "counter0");



I am using Mirth 3.0.1.7051. I tried to use globalChannelMap in the pre-processor and it did not work. When the program first go in, I want to read the counter from a file and add 1 to the counter. The second time it goes in, it should have the counter0 defined. But it is not. I am not sure what I did wrong. Your help is greatly appreciated.

globalChannelMap not working