c# - ASP Parser Error after adding LocalResource file to a user control -

i'm working in vs2012 on asp.net web forms project. have created user control named trips.ascx. had vs auto-generate local resource file me (trips.ascx.resx). after adding resource file, cleaned contain properties/values need. ran fine. duplicated resource file , named trips.ascx.pt.resx support portuguese. reason when run project, parser error described below:

parser error message: type 'telerik.web.ui.gridboundcolumn' not have public property named 'headertextpt'.

i'm not sure appending "pt" "headertext" property.

any thoughts/suggestions why receiving error?

update: notice if create empty resource file named trips.ascx.pt.resx, no errors thrown. when start add entries same name referenced in control (ex: when add "calorieslabelresource1.text" resource key trips.ascx.pt.resx)

for reference, folder structure follows:

-project

--controls

---app_localresources

---trips

----app_localresources

-----trips.ascx.pt.resx

-----trips.ascx.resx

----trips.ascx

...

here code using calling resource:

<telerik:radgrid runat="server"      id="mytripsgrid"      onneeddatasource="mytripsgrid_needdatasource"      allowpaging="true" >     <mastertableview runat="server" autogeneratecolumns="false">         <columns>             <telerik:gridboundcolumn uniquename="datecolumn" headertext="date" datafield="rented" dataformatstring="{0:mm/dd/yy}" meta:resourcekey="dategridboundcolumnresource1" />