custom reports not working.

Hi guys, I'm stuck at generating custom reports using Statistics Collector.

My scenario,

I have an BaaS DB with a collection named "icustomer" which has few name/value pair's.

I created a proxy(icustomer) to display an specific Customer(Resource name- specificcust) depending on unique "cust_id".

For Specific Customer I did "extract variable and assign variable policies" which is working fine.

Now to get custom reports I again added an Extract Variable policy to extract cust_id from JSON Path and then added and Statistic Collector policy to get stats.

Then I created an new report from Analytics and saved it. But reports aren't generated.

Where did I go wrong?

Proxy Link - http://siddharth1-test.apigee.net/icustomer

Extract Variable Policy for stats

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<ExtractVariables async="false" continueOnError="false" enabled="true" name="Extracting-for-Stats">
    <DisplayName>Extracting for Stats</DisplayName>
    <FaultRules/>
    <Properties/>
   
    <IgnoreUnresolvedVariables>true</IgnoreUnresolvedVariables>
    <JSONPayload>
        <Variable name="customer_id">
            <JSONPath>$.cust_id</JSONPath>
        </Variable>
    </JSONPayload>
    <Source clearPayload="false">request</Source>
    <VariablePrefix>apigee</VariablePrefix>
    
</ExtractVariables>

Statistic Collector Policy

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<StatisticsCollector async="false" continueOnError="false" enabled="true" name="Statistics-Collector-1">
    <DisplayName>Statistics Collector 1</DisplayName>
    <FaultRules/>
    <Properties/>
    <Statistics>
        <Statistic name="test_cust_id" ref="customer_id" type="STRING">NO_ID</Statistic>
    </Statistics>
</StatisticsCollector>

Target Endpoint Code

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<TargetEndpoint name="default">
    <Description/>
    <PreFlow name="PreFlow">
        <Request/>
        <Response/>
    </PreFlow>
    <Flows>
        <Flow name="specficcust">
            <Description/>
            <Request>
                <Step>
                    <FaultRules/>
                    <Name>Extract-Variables-1</Name>
                </Step>
                <Step>
                    <FaultRules/>
                    <Name>Assign-Message-1</Name>
                </Step>
            </Request>
            <Response>
                <Step>
                    <FaultRules/>
                    <Name>Extracting-for-Stats</Name>
                </Step>
            </Response>
            <Response>
                <Step>
                    <FaultRules/>
                    <Name>Statistics-Collector-1</Name>
                </Step>
            </Response>
            <Condition>(proxy.pathsuffix MatchesPath "/{cust_id}") and (request.verb = "GET")</Condition>
        </Flow>
    </Flows>
    <PostFlow name="PostFlow">
        <Request/>
        <Response/>
    </PostFlow>
    <HTTPTargetConnection>
        <URL>https://api.usergrid.com/siddharth1/sandbox/icustomer</URL>
    </HTTPTargetConnection>
</TargetEndpoint>

Custom Report Screenshot