PowerShell using system.data.SqlDbType varbinary max error

Question

my setup is: a SQL Server (2016), a Table (Filestream active) with a varbinary(max) column containing some ZIP-Files. There is a stored procedure with an output parameter returning the ZIP-File. I'm using a PowerShell-Function that fires this stored procedure returning the ZIP-File. As long, as the ZIP file is <= 2 GB, there is no problem. All bigger files will not be returned. When I try to debug the script, there is even no Error value. I know the problem is the SQLDBType mapping: [system.data.SqlDbType]::varbinary,-1). Thanks for your help.

1. The table:

   CREATE TABLE [my].[table](
   [datafile] [varbinary](max) FILESTREAM  NULL,
   [checksum] [varchar](100) NULL,
   [build] [varchar](50) NULL)
   

2. the stored procedure:

   create PROCEDURE [my].[getZIPFile]  (
   @ZIPFile varbinary(max) OUTPUT,
   @checkSum varchar(100) OUTPUT,
   @aktScriptVersion decimal(4,2) output
   ) 
   AS 
   BEGIN
   IF ..... = 'SQLBinary'
       BEGIN
           SELECT @ZIPFile = [DataFile], @checkSum = [checksum], @aktScriptVersion = version_nr
           FROM [deployment].[softwarerepository]
       END
   

3. PowerShell-Function

    Function Get-ZIPFile
    {
        param(
        .... some parameter
        )
   
        $conn = New-Object System.Data.SqlClient.SqlConnection
        $conn.ConnectionString = "Server=myServer;Database=myDB;Integrated Security=no;User=SQL_user;Password=xxxxx"
        $conn.Open() | out-null
        $cmd = new-Object System.Data.SqlClient.SqlCommand 
        #Proz
        $cmd.Connection = $conn
        $cmd.CommandType = [System.Data.CommandType]::StoredProcedure
        $cmd.CommandText = "deployment.getZIPFile" # ProzedurName
        #### Proz-Parameter
        #
        $cmd.Parameters.Add("@ZIPFile",[system.data.SqlDbType]::varbinary,-1) | out-Null # HIER MUST BE THE ERROR
        $cmd.Parameters["@ZIPFile"].Value = [System.DBNull]::Value
        $cmd.Parameters['@ZIPFile'].Direction = [system.data.ParameterDirection]::Output
        #
        $cmd.Parameters.Add("@checkSum",[system.data.SqlDbType]::Varchar,100) | out-Null
        $cmd.Parameters['@checkSum'].Direction = [system.data.ParameterDirection]::Output
        #
        $cmd.Parameters.Add("@aktScriptVersion",[system.data.SqlDbType]::decimal) | out-Null
        $cmd.Parameters['@aktScriptVersion'].Direction = [system.data.ParameterDirection]::Output
        $cmd.Parameters['@aktScriptVersion'].Precision=18 #kranke Scheisse! sonst ist die Ausgabe: 3 und nicht 3,01 !!!
        $cmd.Parameters['@aktScriptVersion'].Scale=2
   
        $i = $cmd.ExecuteNonQuery() # DEBUG: NO ERROR!
        $ausgabe = [pscustomobject]@{
            zipFile = ""
            checkSum = ""
            aktScriptVersion = 0
        }
        if($i -gt 0) 
        {
            $ausgabe.zipFile = $cmd.Parameters["@ZIPFile"].Value
            $ausgabe.checkSum = $cmd.Parameters["@checkSum"].Value
            $ausgabe.aktScriptVersion = $cmd.Parameters["@aktScriptVersion"].Value
        }
        $cmd.Dispose()            
        $conn.Close() 
        $conn.Dispose()
        return $ausgabe
    }
   

As I said: when the zip file <= 2 GB it works just fine, otherwise there is no Error and I get nothing. Thanks for your help.