API Powershell Script to Search for IMEI number in Knox Admin Portal to see if it exists?

Question

I am trying write an API PowerShell script that gets the number of total devices in my Knox KME portal. After that is done the script uses the searchstring method in Knox mobile enrollment API to search for a specific IMEI number to see if the imei number exists. I am able to successfully retrieve the total count of devices but I get a "device not found" message when searching for the IMEI number when the IMEI number is actually in KME. $searchString = "350000000" where 350000000 is the IMEI number. Can someone assist me with this? Below is the script I am running in PowerShell.

{
.SYNOPSIS
This script gets devices from KME and searchs for imei number.
.DESCRIPTION
This script uses assemblies created by Samsung to generate and sign JWT and access tokens with 
 the keys.json file. To run this script you need a keys.json file downloaded from your
Samsung Knox portal and a generated Client Identifier.
All needed assemblies are stored in the "NotLoaded" folder and are copied to "SupportFiles" 
once the script runs.

keys.json needs to be stored in "SupportFiles".
.NOTES
Written by: me
Version: 1.0
$notLoaded = Get-ChildItem -Path "$PSScriptRoot\SupportFiles\NotLoaded" -File

#If assemblies has not benn copied to SupportFiles, copy each assembly
if ( -not (Test-Path -path "$PSScriptRoot\SupportFiles\*.dll")) {
Write-Host -ForegroundColor Green "Copying assemblies to supportfiles"
foreach ($file in $notLoaded) {
    Copy-Item -Path $file.FullName -Destination "$PSScriptRoot\SupportFiles" -Force
}
}

sleep 2
function Get-SignedJwt {

param(
    [Parameter(Mandatory = $true)]
    [string]$jsonPath,
    [string]$clientID
)

#Load assemblies
Add-Type -Path "$PSScriptRoot\SupportFiles\Microsoft.CSharp.dll"
Add-Type -Path "$PSScriptRoot\SupportFiles\Microsoft.IdentityModel.Logging.dll"
Add-Type -Path "$PSScriptRoot\SupportFiles\System.Security.Cryptography.Cng.dll"
Add-Type -Path "$PSScriptRoot\SupportFiles\Microsoft.IdentityModel.Tokens.dll"
Add-Type -Path "$PSScriptRoot\SupportFiles\Microsoft.IdentityModel.JsonWebTokens.dll"
Add-Type -Path "$PSScriptRoot\SupportFiles\Newtonsoft.Json.dll"
Add-Type -Path "$PSScriptRoot\SupportFiles\BouncyCastle.Crypto.dll"
Add-Type -Path "$PSScriptRoot\SupportFiles\knoxAPIUtility.dll"

#Generate signed JWT
try {
    $script:signedClientId = 
[knoxAPIUtility.KnoxTokenUtility]::generateSignedClientIdentifierJWT("$jsonPath", "$clientID")
}
catch {
    Write-Error $_.Exception | format-list -force
    Break
}
}

function Get-AccessToken {

param(
    [Parameter(Mandatory = $true)]
    [string]$jsonPath
)

#Get json content from keys.json
$keyJson = Get-Content $jsonPath | ConvertFrom-Json
$pubKey = $keyJson.public

#Build body for access token request
$body = [ordered]@{
    clientIdentifierJwt          = "$signedClientId"
    base64EncodedStringPublicKey = "$pubKey"
    #validityForAccessTokenInMinutes = 30
}

#Convert body to json format
$requestObject = $body | ConvertTo-Json

$requestbody = @"
$requestObject
"@

#Set access token request headers
$Headers = @{’Content-type’ = ‘application/json’ }

#If JWT has been generated, request access token
if ($body.clientIdentifierJwt) {
    $tokenquery = Invoke-RestMethod -Method Post -Uri "https://us-kcs- 
api.samsungknox.com/ams/v1/users/accesstoken" -Body $requestBody -Headers $Headers
}
else {
    Write-Error "Not able to get JWT"
}

#If access token request failed, break
if (!$tokenquery.accesstoken) {
    Write-Error "Not able to get access token"
    Break
}
else {
    try {
        $script:signedAccessToken = 
[knoxAPIUtility.KnoxTokenUtility]::generateSignedAccessTokenJWT("$jsonPath", 
$tokenquery.accessToken)
    }
    catch {
        Write-Error $_.Exception | format-list -force
        Break
    }
}
}

#Generate JWT
Write-Host -ForegroundColor Cyan "Generating signed JWT"
Get-SignedJwt -jsonPath "$PSScriptRoot\SupportFiles\keys.json" -clientID "client_ID_here"

sleep 2

#Get access token and sign with KnoxAPI utility
Write-Host -ForegroundColor Cyan "Getting access token and signing the token"
Get-AccessToken -jsonPath "$PSScriptRoot\SupportFiles\keys.json"

#Check if JTW and Token has been generated, if not, break
if (!$signedClientId -or !$signedAccessToken) {
Write-Error "not able to generate signed JWT or access token"
break
}

sleep 2

 #If access token is generated get devices
if ($signedAccessToken) {
$Headers = @{’Content-type’ = ‘application/json’; 'x-knox-apitoken' = "$signedAccessToken"}


$devicequery = Invoke-RestMethod -Method Get -Uri "https://us-kcs- 
api.samsungknox.com/kcs/v1/kme/devices/list" -Headers $Headers
Write-Host -ForegroundColor Yellow "Found $($devicequery.totalCount) devices"


}

 sleep 2

$searchString = "350000000"
#Add the search string for the device model or serial number you want to search

$url = "https://central.samsungknox.com/itadmin/kme/devices?searchString=$searchString"
$headers = @{ "Authorization" = "Bearer $signedAccessToken" }

$response = Invoke-RestMethod -Uri $url -Headers $headers -Method Get

if ($response.data -ne $null) {
 Write-Host "Devices found:"
 $response.data | Format-List
} else {
 Write-Host "No devices found."} 
}