Two Plugins not showing in CP after pushing to staging server Two different plugins not showing in the CP after code was pushed to staging server.

My questions:  

1) Why wouldn't the plugins show in CP if plugins are present in the craft_plugins table?

2) How to troubleshoot this issue?  I'm not seeing any plugin errors in php-error.log or craft.log.

What I know:

-- Two plugins are NOT showing:


truncHTML ( my own custom twigFilter )  
the "Import" plugin (
boboldehampsink v 0.7.1- latest)
Other plugins load fine. 


-- Both "missing" plugins are present in the craft_plugins table. 

-- Site seems to work file except for missing plugins, and related missing twig filter template error:

The filter "truncHTML" does not exist 


-- My Development environment is php 5.4.24.
-- Staging is PHP 5.3.3 (where Plugins not loading) 


I confirmed that all Craft required PHP extensions are loading on the staging server


-- Craft dev mode enabled. 

-- a similar truncate twig filter plugin loads fine.  

2014/07/30 00:51:58 [trace] [system.CModule] Loading "plugins" application component
in /var/www/craft.dev/craft/app/etc/web/WebApp.php (594)
in /var/www/craft.dev/craft/app/etc/web/WebApp.php (226)
in /var/www/craft.dev/craft/app/index.php (196)
2014/07/30 00:51:58 [trace] [system.db.CDbCommand] Querying SQL: SELECT `id`, `class`, `version`, `settings`, `installDate`
FROM `craft_plugins`
WHERE enabled=1
in /var/www/craft.dev/craft/app/services/PluginsService.php (101)
in /var/www/craft.dev/craft/app/etc/web/WebApp.php (226)
in /var/www/craft.dev/craft/app/index.php (196)
2014/07/30 00:51:58 [profile] [system.db.CDbCommand.query] begin:system.db.CDbCommand.query(SELECT `id`, `class`, `version`, `settings`, `installDate`
FROM `craft_plugins`
WHERE enabled=1)
2014/07/30 00:51:58 [profile] [system.db.CDbCommand.query] end:system.db.CDbCommand.query(SELECT `id`, `class`, `version`, `settings`, `installDate`
FROM `craft_plugins`
WHERE enabled=1)
2014/07/30 00:51:58 [trace] [system.CModule] Loading "messages" application component
in /var/www/craft.dev/craft/app/etc/web/WebApp.php (594)
in /var/www/craft.dev/craft/app/Craft.php (402)
in /var/www/craft.dev/craft/plugins/truncate/TruncatePlugin.php (13)
2014/07/30 00:51:58 [trace] [system.CModule] Loading "i18n" application component
in /var/www/craft.dev/craft/app/etc/web/WebApp.php (594)
in /var/www/craft.dev/craft/app/etc/web/WebApp.php (826)
in /var/www/craft.dev/craft/app/etc/web/WebApp.php (293)


-- I can include a stack trace detailing the twig "missing filter" error resulting from missing twig filter plugin, but I don't think this helps explain the missing plugin.   

Any Ideas?  Thanks!!
Check if the plugin folders in craft/plugins are named correctly. Most local environments aren't case-sensitive, but most servers are.

Valid:

craft/plugins/trunchtml/
craft/plugins/import/

Invalid:

craft/plugins/truncHTML/
craft/plugins/Import/