Well I have now version 4.0.8 and cant updgrade to the newer - I get this error:

Fatal error: Call to a member function children() on a non-object in /data/www/www_fotobanky_cz/tmp/install_4e4a33f2f080c/upgrade/4.0.9.php on line 77

So what do you suggest?
Uninstall the whole plugin and install it again? If yes, what version - the newest free version or the one, that I purchased?

I upgraded to JoomSEF 4.0.8, but the problem is still same :(

Provided Download ID is not valid for the requested file: com_joomsef3.zip. Please, make sure you are using valid Download ID for this product. (com_joomsef4.zip)

So what now? Please help.

No, I don't use any other joomsef plugin. So what is the solution?

Just looking at it again and again and maybe the error is in versions? Check my first message:

I have Joomla! 1.6.3 Stable [ Onward ] 18-Apr-2011 23:00 GMT with installed JoomSEF version 4.0.4
...
Provided Download ID is not valid for the requested file: com_joomsef3.zip. Please, make sure you are using valid Download ID for this product. (com_joomsef3.zip)

Why there is once com_joomsef3.zip and then com_joomsef3.zip??

I have still the problem described above. Can you please look at it? Or I just throw away my money?

I checked the download ID several times...

Hi,
I have Joomla! 1.6.3 Stable [ Onward ] 18-Apr-2011 23:00 GMT with installed JoomSEF version 4.0.4. I bought the JoomSEF plugin, but don't know, how to register in Joomla Admin.

I tried "Online Upgrade to Paid Version" in Upgrade tab, but get this message:

Provided Download ID is not valid for the requested file: com_joomsef3.zip. Please, make sure you are using valid Download ID for this product. (com_joomsef4.zip)

So I downloaded the com_joomsef4.zip from the site, but when I'm trying to install it (via "Upload Package File" in Upgrade tab) I got this error message:

Fatal error: Call to a member function children() on a non-object in /data/www/www_fotobanky_cz/tmp/install_4e41ab876511b/upgrade/4.0.9.php on line 77

Can you help me? I still have the advertisement links on my site.