I have created a custom user field as follows
<Field
ID="{9B49F1A5-7FFB-400B-9B0E-0FC4D6C1417C}"
Name="AMtalatFieldEditors"
DisplayName="My Editors"
Type="UserMulti"
Mult="TRUE"
Required="TRUE"
ShowField="FirstName"
StaticName="AMtalatFieldEditors"
SourceID="http://schemas.microsoft.com/sharepoint/v3"
Customization=""
UserSelectionMode="PeopleOnly"
UserSelectionScope="0"
Group="MyGroup"
ShowInNewForm="TRUE">
</Field>
added it to my content type
<FieldRef ID="{9B49F1A5-7FFB-400B-9B0E-0FC4D6C1417C}" Name="AMtalatFieldEditors" DisplayName="My Editors" Required="TRUE" Customization="" ShowInNewForm="TRUE"/>
add it to the page layout
<div id="editorsDiv">
<SharePointWebControls:UserField ID="AMtalatFieldEditors" FieldName="AMtalatFieldEditors" runat="server" />
</div>
I edit a page and change the page layout to the mine and fill out the user field and click on Save. But the value of user field is disappeared and when I click on Check in, it says: Error: you have to fill out the required property and when I click on "OK" it redirects me to the page to fill the properties. it seems I never can check in my pages.