CRUD Validation Error: Value is not valid

Hello
I'm using NetBeans 6.8 to write a CRUD app with several tables.
Some of the entities have string-type primary keys and some have Integer-type
primary keys.
One such entity is defined as Member and another is defined as Center.
Centers have an Integer-type primary key called CenterId.

The problem I'm having is in the creation of a New Member
The fields for Member are:
MemberID, FirstName LastName and CenterID.
CenterID is defined as a foreign key related to Center.
My New.jsp for Member uses a SelectOneMenuItem tag like this

Code:

---

                    <h:outputText value="Member ID:"/>
                    <h:inputText id="memberId" value="#{MemberMB.member.memberId}" title="Member ID" required="true" requiredMessage="The orderNum field is required." />
                    <h:outputText value="First Name:"/>
                    <h:inputText id="firstName" value="#{MemberMB.member.firstName}" title="First Name" />
                    <h:outputText value="Last Name:"/>
                    <h:inputText id="lastName" value="#{MemberMB.member.lastName}" title="Last Name" />
                    <h:outputText value="Join Date:MM/dd/yyyy):"/>
                    <h:inputText id="joinDate" value="#{MemberMB.member.joinDate}" title="Join Date" >
                        <f:convertDateTime type="DATE" pattern="MM/dd/yyyy" />
                    </h:inputText>
                    <h:outputText value="Center ID:"/>
                    <h:selectOneMenu id="centerId" value="#{MemberMB.member.centerId}" title="centerId" required="true" requiredMessage="The CenterId field is required." >
                        <f:selectItems value="#{CenterMB.centerItemsAvailableSelectOne}"/>
                    </h:selectOneMenu>

---

The jsp displays fine but when I select a CenterId fron the combobox and tryt to create, I get the JSF Framework Exception:
j_id_id20:centerId: Validation Error: Value is not valid
Can anyone help with this?
I've used the same procedure with other entities that have String-type primary key and it works fine.
-J