Christian,

 

Please open the dotnetgallerymodule.ascx file.

 

And check the FoldPath property.

 

For example,

<CE:Gallery
    id="gallery1"
    runat="server"
    Height="300"
    Width="600"
    Column = "8"
    MaxImageWidth="600"
    CellPadding="3"  
    AutoResizeUploadedImages = "true"  
    CellSpacing="3"
    ForeColor="#000000"
    BorderStyle="solid"
    BorderWidth="0"
    CssClass="container"
    ShowThumbNailName="true" 
    ShowBatchBuild = "False"
    ShowThumbNailDescription = "False"
    ShowThumbNailSize="true" 
    ShowThumbNailDate="false" 
    FilesPath  = "~/DesktopModules/dotnetgallery/DotNetGallery_Files"
    FolderPath = "/samplefolder/"
   >
   </CE:Gallery> 

 

Make sure that folder does exist on your server.