Handling missed nodes in xml while using Xpath

HI i am facing an situation where i need to iterate over an xml to find the required data my xml structure is as follows and i am using following xpath query to find node children where area = some value. But this structure repeats several times in xml where some dont have node, i mean node is missing. so when i try to use Xpath for iterating over xml it is giving error checkin text missing. How can i handle this error.please help me

XPathDocument document = new XPathDocument(gFilepathName);
            XPathNavigator navigator = document.CreateNavigator();

            XPathNodeIterator nodes = navigator.Select("ReleaseNotes/ChangeSet/Comments/checkintext/task[area='"+functionalArea+"']");

<ChangeSet>
        <CheckinID>3375</CheckinID>
        <CheckinBy>INNOVITES\nagaprasad.k</CheckinBy>
        <Comments>
            <checkintext>
                <bpcheckdeviated>true</bpcheckdeviated>
                <task>
                    <id>CS-2024</id>
                    <name>Selected dimensions not shown in production sequencing form.</name>
                    <version>V6.0</version>
                    <sprint>84</sprint>
                    <project>Cs2024_Prd_CorrectDimensionDisplay</project>
                    <area>40. Production</area>
                    <taskstatus>Closed</taskstatus>
                </task>
                <text>
                    1. Components check-in for correct dimensions display based on set-up.
                    2. Previously InventDimensions group was removed, now we restored previous version and set visibility no. InventoryDimensions group is kept as it was.
                </text>
                <notes />
            </checkintext>
        </Comments>
        <Changes>
            <Component>
                <Name>CsPsqProdSequence.xpo</Name>
                <Type>Forms</Type>
                <Action>Edit</Action>
            </Component>
        </Changes>
    </ChangeSet>