EWS ContactGroup can't edit from OWA

I have created contactgroups for all of my users but I am finding that the groups I created are not able to be edited in OWA. I can edit them from Outlook, but the majority of our users are using only OWA. Here is the code I used.

// Create new contact object
ContactGroup contactGroup = new ContactGroup(Service);

// Set display name
contactGroup.DisplayName = card.FormattedName;

// Loop throgh email addresses
for (int j = 0; j < card.EmailAddresses.Count(); j++)
{
// Create a group member
GroupMember gm = new GroupMember(card.EmailAddresses[j].Address, card.EmailAddresses[j].Address);

// Add members to the group
contactGroup.Members.Add(gm);
}

// Save contact group
contactGroup.Save();