(You are passing control name as string and within the function, using it as a control. [string != control])
Here is the fix:
1. Rename your checkbox name attribute same as id.
2. Pass control name as parameter.
<input id="CHAMPARAN_EAST" name="CHAMPARAN_EAST" onclick="SearchDistict('CHAMPARAN_EAST');" type="checkbox" value="34">
function SearchDistict(obj)
{
var ctrl = $("#"+ obj);