Installation didn't went well

I've got two hosting locations.

1 location where I made a mobile joomla template and 1 location with the actual website where I have to put the template when it's ready.

Everything on the test location went well.
Now, the template is ready, so I want to install it on the actual website.

The installation went well. No errors. Only on the main menu (back-end) it didn't show the mobile joomla logo.
Then I copied all the files from the working test location to the normal website.
Now I saw the button and it said I needed an update. I downloaded the update, so that should be correct now.

But still the mobile website doesn't work if I add ?device=xhtml behind the website url.

All the information I have:

Versions:
Joomla: 1.5.25
Mobile Joomla: 1.2.2

Hostingprovider:
www.vevida.nl

Hosting package:
standaard hostingpakket .nl

Site address:
www.snack-plaza.nl

I tested on android devices in the normal browser and on windows7 with chrome.
It does work on the test server, but not on the actual server.

ASP, PHP 5 en Perl 5.8
ASP.NET 3.5 en 2.0

I do not see any error message atm.

I did read the FAQ, but couldn't find anything that looks like this.

Thanks for your help!

I noticed two error messages.

In the back-end in advanced settings.
When I click on Modules I get this message:
Fatal error: Class 'plgSystemMobileBot' not found in D:\www\snack-plaza.nl\www\administrator\components\com_mobilejoomla\admin_tpl\modules.php on line 25

When I click on Plugins i get this message:
Fatal error: Class 'plgSystemMobileBot' not found in D:\www\snack-plaza.nl\www\administrator\components\com_mobilejoomla\admin_tpl\plugins.php on line 46

I don't know if it's related, but just to let you know.

Most likely "MobileJoomla" system plugin is disabled. Check it.

This probably was the problem 

Thanks! 

Now I've got another strange problem.
When I want to select the right template for smartphones, this one is missing in the list.

Allready fixed.

Now I have another problem again 

When I add a menu item with an article, I get this message:

Fatal error: Call to a member function get() on a non-object in D:\www\snack-plaza.nl\www\templates\mobile_smartphone\html\com_content\article\default.php on line 6

Nvm, I replaced the default.php with the original one.

It doesn't really go very smooth
The desktop template isn't shown now.

It shows the mobile template even though the desktop template is standard.

Edit:
device=desktop...