Debugging unfound migration

I've used migrate 2 with a CSV source successfully before.
However, on what-seems-to-me a simpler project, I can't get the migration to register (migrate UI shows 'no migrations').
I've checked the .info and .module and csv path a million times for typos, and cleared the cache everytime, to no avail, and as such, am wondering if there are any debugging techniques for troubleshooting where the module goes awry. I can't get it to give me an error or anything. Just doesn't show.

info:

name = "Products Migrate"
description = "product migration data from csv"
package = "Development"

dependencies[] = migrate
dependencies[] = migrate_ui

files[] = my_module.migrate.inc

version = "7.x-1.0"
core = "7.x"

.module is just the stock code to set api level to 2
no .install file - I don't think I need one for a .csv import, do I? (I actually tried creating an install file in desperation, but to no avail)

.inc:

<?php
abstract class my_module_BasicMigration extends Migration {
  public function __construct() {
    // Always call the parent constructor first for basic setup
    parent::__construct();
  }
}

class my_module_ChairMigration extends my_module_BasicMigration {
  public function __construct() {
    parent::__construct();
    $this->description = t('Import Chairs into Product:Chair content type');
    $columns = array(
      // "Source": ('Fieldname', 'Description')
      0 => array('cat_number', t('Catalogue number (must be unique)')),
      1 => array('name', t('Product name')),
      2 => array('cat_page', t('Catalogue page')),
      3 => array('brief_desc', t('Brief Description')),
      4 => array('full_desc', t('Full description')),
      5 => array('designer', t('Designer')),
      6 => array('width', t('Width')),
      7 => array('depth', t('Depth')),
      8 => array('height', t('Height')),
      9 => array('seat_height', t('Seat Height')),
      10 => array('price', t('Price')),
      11 => array('stool-bool', t('Is it a stool'))
    );
    $this->source = new MigrateSourceCSV(DRUPAL_ROOT . '/' . drupal_get_path('module', my_module') . '/data_sources/importchairs.csv', $columns);
		$this->destination = new MigrateDestinationNode('product_chair');
    $this->map = new MigrateSQLMap($this->machineName,
        array('chid' => array(
                'type' => 'int',
                'not null' => TRUE,
                'description' => t('chair-ID') // description never used
              )
             ),
        MigrateDestinationNode::getKeySchema()
    );
	 $this->addFieldMapping('title', 'name')
      ->defaultValue('')
      ->description(t('Product name'));
   $this->addFieldMapping('field_cat_number', 'cat_number')
      ->defaultValue('')
      ->description(t('Catologue number'));
    $this->addFieldMapping('field_cat_page', 'cat_page')
	      ->defaultValue('')
	      ->description(t('Catalogue number'));
    $this->addFieldMapping('body', 'full_desc');
    $this->addFieldMapping('field_designer', 'designer')
      ->defaultValue('');
    $this->addFieldMapping('field_width', 'width')
      ->defaultValue('');
		$this->addFieldMapping('field_depth', 'depth')
      ->defaultValue('');
		$this->addFieldMapping('field_height', 'height')
      ->defaultValue('');
		$this->addFieldMapping('field_seat_height', 'seat_height')
      ->defaultValue('');
    $this->addFieldMapping('field_price', 'price')
      ->defaultValue('');
		$this->addFieldMapping('field_chair_form', 'stool-bool')
      ->defaultValue(0);
		$this->addFieldMapping('uid')
		 ->defaultValue(13);
		// Other handlers
    $this->addFieldMapping('path')
      ->defaultValue(NULL);
    if (module_exists('pathauto')) {
      $this->addFieldMapping('pathauto')
        ->defaultValue(''); // Perform aliasing (set to 0 to prevent alias generation during migration)
    }
  }
}

That's all there is to it. Thoughts?