CRM2011 Data Filtering and retrieve

Following code illustrate how to Filter the data in the CRM and retrieve data from it in following code I have Select "Paidamount " form "Eventbooking" Entity for that I need to satisfy following criteria 
PaidAmount should not null, Bookingstatus should be 2, StatusCode should be 1 and event id must have to equal to provide one of the top 

// Enter Guid of Event
Guid eventId = new Guid('46835C46-C059-422D-BF94-F4507ECE0F14')

FilterExpression filter = new FilterExpression();

// Check Eventid == eventId;
ConditionExpression condition = new ConditionExpression();
condition.AttributeName = "Eventid";
condition.Operator = ConditionOperator.Equal;
condition.Values.Add(eventId);
filter.AddCondition(condition);

// Check Paidamount != null;
condition = new ConditionExpression();
condition.AttributeName = "Paidamount";
condition.Operator = ConditionOperator.NotNull;
filter.AddCondition(condition);

// Check booktatus== 2;
condition = new ConditionExpression();
condition.AttributeName = "booktatus";
condition.Operator = ConditionOperator.Equal;
condition.Values.Add(2);
filter.AddCondition(condition);

// Check statuscode== 1;
condition = new ConditionExpression();
condition.AttributeName = "statuscode";
condition.Operator = ConditionOperator.Equal;
condition.Values.Add(1);
filter.AddCondition(condition);

// Set QueryExpression for  Eventbooking
QueryExpression query = new QueryExpression("Eventbooking");

// Select Paidamount Field
query.ColumnSet = new ColumnSet("Paidamount");

// Add filter to query               
query.Criteria.AddFilter(filter);

// Retrive Paidamount List
var actualEventIncome = RetrieveMultiple(query).ToList();