File upload error 'A server error occurred while uploading the file'

I've been trying to create a simple single file upload. But I keep getting the error 'A server error occurred while uploading the file'

My js file contains the following code where the table name is called 'deenk_files' and the primary key of the table is file_id

            {
                label: "Image:",
                name: "image",
                type: "upload",
                display: function ( file_id ) {
                    return '<img src="'+editor.file( 'deenk_files', file_id ).web_path+'"/>';
                },
                clearText: "Clear",
                noImageText: 'No image'
            }

My php file contains the following code.

Field::inst( 'image' )
            ->setFormatter( Format::ifEmpty( null ) )
            ->upload( Upload::inst( 'D:\data/test.png' )
                ->db( 'deenk_files', 'file_id', array(
                    'filename'    => Upload::DB_FILE_NAME,
                    'filesize'    => Upload::DB_FILE_SIZE,
                    'web_path'    => Upload::DB_WEB_PATH,
                    'system_path' => Upload::DB_SYSTEM_PATH
                ) )
            )

Any idea what is going wrong here?