Problem with height of Part in a List page

gtrennert2

Hello
I have a page like this :
A Page with PageType = List, containing a group of 3 fields and a repeater
and at the end a part page (PageType = ListPart)
the part page has to show lines that refer to the record selected in the list page
Problem is that this part page has a height problem like here in this picture :

    PageType = List;
    ApplicationArea = All;
    UsageCategory = History;
    SourceTable = "xxx";
    CaptionML = FRA = 'xxx', ENU = 'xxx';
    InsertAllowed = false;
    DeleteAllowed = false;

    layout
    {
        area(Content)
        {
            group("Fichier Interface")
            {
            ...
            }
            repeater(GroupName)
            {
            ...
            }
            group(msg)
            {
                ShowCaption = false;
                part("yyy"; "yyy")
                {
                    ApplicationArea = All;
                    SubPageLink = ...;
                }
            }
        }
    }
}

What's going wrong ?
Thanks