When you have more than one "blob" field on a table, the admin web page generated for that table causes a runtime error. The \ASP.NET\Common\Admin\Entity.aspx.cst has a const string _blobTemplate, which assumes that only one blob field exists for one table. I corrected the issue by adding an addition format statement.
const string _blobTemplate =@" ...
...
<itemtemplate>
<ajaxToolkit:ModalPopupExtender id='ModalPopupExtender{3}' runat='server'
TargetControlID='LinkButton{3}'
PopupControlID='Panel1'
OkControlID='Button1'
BackgroundCssClass='ModalBackground'
DynamicControlID='lblPreview'
DynamicContextKey='<%# DataBinder.Eval(Container.DataItem, ""{2}"") %>'
DynamicServiceMethod='Get{1}Content' />
<asp:LinkButton ID='LinkButton{3}' runat='server' Text='Preview' />
</itemtemplate>
In addition, line 107: Response.Write(WriteBlobTemplateField(column, suffix) + "\r\n");
lines 311-315:
public string WriteBlobTemplateField(ColumnSchema column, int suffix)
{
string propertyName = GetPropertyName(column);
return string.Format(_blobTemplate, GetFriendlyName(column), propertyName, GetPropertyName(SourceTable.PrimaryKey.MemberColumns[0]), suffix);
}