Global Variable Not Getting Value - powershell-4.0

Question

I am wanting to get the row count from each iteration of my Function and assign it to a variable so I can send the results in an email at the end. My syntax produced an error of this which says to me the $rowcount is never actually being assigned to it?
Send-MailMessage: Cannot validate argument on parameter 'Body'. The argument is null or empty. Provide an argument that is not null or empty, and then try the command again.
#Declaring Global Variable
$myArray = $null
$GoodSyntax = "Select * From tableunknown"
$extractFile = "C:\Test.csv"
$dirName = "C:\Completed\"
$date = Get-Date -f 'MM.dd.yy'
#Call function
Execute-SQLquery
if (Execute-SQLquery $GoodSyntax)
$EmailBody = $myArray | Out-String
send-mailmessage -to "abc123#gmail.com" -from "barkbarksalon123#gmail.com" -Body $EmailBody -BodyAsHtml:$true -subject "Testing Through Powershell"
Function Execute-SQLquery {
param ($GoodSyntax)
$server = "Server01"
$database = "database01"
$connectionTemplate = "Data Source={0};Integrated Security=SSPI;Initial Catalog={1};"
$connectionString = [string]::Format($connectionTemplate, $server, $database)
$connection = New-Object System.Data.SqlClient.SqlConnection
$connection.ConnectionString = $connectionString
$command = New-Object System.Data.SqlClient.SqlCommand
$command.CommandText = $QueryString
$command.Connection = $connection
$SqlAdapter = New-Object System.Data.SqlClient.SqlDataAdapter
$SqlAdapter.SelectCommand = $command
$DataSet = New-Object System.Data.DataSet
$rowCount = $SqlAdapter.Fill($DataSet)
if ($rowCount -gt 0)
{
[System.IO.Directory]::CreateDirectory($dirName)
$filename = [IO.Path]::GetFileNameWithoutExtension($extractFile) + "_$date" + [IO.Path]::GetExtension($extractFile)
$extractFile = Join-Path $dirname $filename
$DataSet.Tables[0] | Export-Csv $extractFile -NoTypeInformation
$myArray += $rowCount
}
$connection.Close()
}

Answer 1

$rowCount isn't global ... global variables are listed at the top of your code ... it should read like this ...
#Declaring Global Variable
$myArray = $null
$rowCount = 0
$GoodSyntax = "Select * From tableunknown"
...
Make sense?
EDIT:
My bad! I see you are adding $rowCount to $myArray ... that wasn't clear from your question.
Try this ...
#Declaring Global Variable
$rowCountTotal = 0
$GoodSyntax = "Select * From tableunknown"
...
$EmailBody = $rowCountTotal | Out-String
...
$DataSet.Tables[0] | Export-Csv $extractFile -NoTypeInformation
$rowCountTotal += $rowCount
}