How do I test if citation number already exist in database?

What I am trying to do is to use an array to check if citation number in xml document already exist in the database.
If the citation number is not found, the first slot in the returned array will contain the value "No Matching Case".
If the number exist then the number will be displayed in the array.
I need to call GetCaseNumbersForCitation method (astringCitationNumber, ablnUsePrimaryDatasourceOnly) from the library.
Parameters – astrCitationNumber (String) is the Citation Number, ablnUsePrimaryDatasourceOnly (Boolean) allows you to specify whether the replica can be used for this query or not

My shared sub TestCitationGetCaseNumber() code has an error Value of type '1-dimensional array of String' cannot be converted to 'String'.

Code:

---

Public Shared Function GetCaseNumbersForCitation (astrCitationNumber As String, ablnUsePrimaryDatasourceOnly As Boolean) As String()

---

Here is my test code

Code:

---

Option Explicit On
Option Strict On
Imports System.IO
Imports System.Xml
'Imports Msc.Integration.Mncis.Library.v4 which has Citation.vb code and the method to call GetCaseNumbersForCitation

Public Class Test_Code

    Public Shared Sub main()
        TestCitationGetCaseNumber()
    End Sub

    Shared Sub TestCitationGetCaseNumber()
    Dim strCitationNumber As String
    Dim strCitationORI As String
    strCitationNumber = Msc.Integration.Mncis.Library.v4.Citation.GetCaseNumbersForCitation(strCitationNumber, strCitationORI)

    End Sub
End Class

---

Xml document

Code:

---

<?xml version="1.0" encoding="UTF-8"?>
                <NS1:JuvenileCitationDocument xmlns:NS1="http://www.courts.state.mn.us/CourtXML/3" schemaVersion="3:3" messageProducedDateTime="2016-07-01T08:33:17.2276598-05:00" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.courts.state.mn.us/CourtXML/3 file:///H:/Deve/Schemas/CourtXML/JuvenileCitationDocument_3_3.xsd">
                        <NS1:EFileID>
                                <NS1:ID>321</NS1:ID>
                        </NS1:EFileID>
                        <NS1:SubmittingAgencyORI>
                                <NS1:ID>MN027013A</NS1:ID>
                        </NS1:SubmittingAgencyORI>
                        <NS1:Filing>
                                <NS1:ProsecutingAgencyORI>
                                        <NS1:ID>MN027013A</NS1:ID>
                                </NS1:ProsecutingAgencyORI>
                                <NS1:CourtJurisdictionORI>
                                        <NS1:ID>MN027055J</NS1:ID>
                                </NS1:CourtJurisdictionORI>
                                <NS1:OtherAgencyNumber>
                                        <NS1:ID>16J07491</NS1:ID>
                                        <NS1:IDTypeCodeText>PRSF</NS1:IDTypeCodeText>
                                </NS1:OtherAgencyNumber>
                                <NS1:ChargingDecisionTypeText>Juvenile Petty Offense</NS1:ChargingDecisionTypeText>
                        </NS1:Filing>
                        <NS1:Citation>
                                <NS1:CitationNumber>
                                        <NS1:ID>2770043451</NS1:ID>
                                </NS1:CitationNumber>
                                <NS1:IssuingAgencyORI>
                                        <NS1:ID>MN0271100</NS1:ID>
                                </NS1:IssuingAgencyORI>
                </NS1:JuvenileCitationDocument>

---