The complete rule

The two blocks need to be added together (the blocks to calculate the score go before the closing 

</responseProcessing>

 tag -  i.e. after the blocks which link the variables). 

The full response processing rule for his item is now the following:

<responseProcessing>

    <responseCondition>

        <responseIf>

            <not>

                <isNull>

                    <variable identifier="RESPONSE_1" />

                </isNull>

            </not>

            <setOutcomeValue identifier="SCORE_1">

                <mapResponse identifier="RESPONSE_1" />

            </setOutcomeValue>

        </responseIf>

    </responseCondition>

    <responseCondition>

        <responseIf>

            <not>

                <isNull>

                    <variable identifier="RESPONSE_2" />

                </isNull>

            </not>

            <setOutcomeValue identifier="SCORE_2">

                <mapResponse identifier="RESPONSE_2" />

            </setOutcomeValue>

        </responseIf>

    </responseCondition>

    <responseCondition>

        <responseIf>

            <not>

                <isNull>

                    <variable identifier="RESPONSE_3" />

                </isNull>

            </not>

            <setOutcomeValue identifier="SCORE_3">

                <mapResponse identifier="RESPONSE_3" />

            </setOutcomeValue>

        </responseIf>

    </responseCondition>

    <setOutcomeValue identifier="SCORE">

        <sum>

            <variable identifier="SCORE_1" />

            <variable identifier="SCORE_2" />

            <variable identifier="SCORE_3" />

        </sum>

    </setOutcomeValue>

    <setOutcomeValue identifier="MAXSCORE">

        <baseValue baseType="integer">

            9

        </baseValue>

    </setOutcomeValue>

</responseProcessing>