Warning on field settings form after ajax callback (image field)

Hello,

I have an error message when i set the number of initial fields after ajax callback.

Warning : end() [function.end]: Passed variable is not an array or object in file_managed_file_validate() (line 536 in D:\Sites\Mysite\modules\file\file.module).

And another ones on edit mode like:

Undefined index: #max_delta dans multivalue_settings_field_attach_form() (line 43 in D:\Sites\Mysite\sites\all\modules\multivalue_settings\multivalue_settings.module).
Notice : Undefined index: #max_delta dans multivalue_settings_add_item() (line165 in D:\Sites\Mysite\sites\all\modules\multivalue_settings\multivalue_settings.module).
Notice : Undefined index: dans multivalue_settings_add_item() (line168 in D:\Sites\Mysite\sites\all\modules\multivalue_settings\multivalue_settings.module).

Any ideas about that?

thanks a lot!