C-moi,
I have good news and a bad one.
I downloaded your xmltv.xml and tvguide.xml files. I'm not sure how you use your xmltv.xml - it does not have "start" and "stop" attributes in the <programme> tag ex:
<programme channel="1:0:1:1AF9:3FE:1:C00000:0:0:0:">
so, the xlobby was able to load it somehow (but it only shows channels, no programs), plug-in started the search, but error out due to that - sorry, but you will not be able to use this file
On the other hand tvguide.xml was perfect. I had no problems loading it and searching. Here are 2 screens with my test skin:
here I searched for "les sumos" and found 3 matches
and here for "magazine" as a category and found 799 matches
So, the good news was that your file is searchable with my plug-in, but the bad is that as far as the error goes, I'm a little confused. You are using my test skin, right? From the error, it looks like "Search" command is missing (or has incorrect) parameter and XL can't execute it - it should be the name of the category "xepgsearch", if you could double check that and let me know and I'll look at the code and double check the the 'search' command.
EDIT: Well, I took a second look at the code, I can't really see anything that would jump at me. I added some error handling code, so maybe this will help determine what the problem is. If you could try downloading the plug-in again.
EDIT II: What is the version/date of your xlobby and XPluginSDK.dll?