The resource class for this page was not found. Please check if the resource file exists and try again.

hello,

i have app_localResources in my projects.
ddlCountry.Items.Insert(0, new ListItem(GetLocalResourceObject("ListItemPleaseSelect").ToString(), "null"));
returns:
The resource class for this page was not found.  Please check if the resource file exists and try again.

I have my aspx in Template/Default but i have also in other folder Template/Test.
How can I used
ddlCountry.Items.Insert(0, new ListItem(GetLocalResourceObject("ListItemPleaseSelect").ToString(), "null")); in this case?
Please help