Here, here is my JavaScript code within a VisualForce page. The query is guaranteed to return only one result. but I am getting "Invalid Session ID" exception. please help.
function queryPricingModel()
{
sforce.connection.sessionId = '{!$Api.Session_ID}';
try
{
var myQuery = sforce.connection.query("SELECT BP__c FROM PC_BP_Matrix__c WHERE StartVolume__c <= annualVolume AND EndVolume__c > annualVolume");
pcBP = myQuery;
}
catch (error)
{
alert(error.faultstring);
}
}