"Cannot get Membership Provider with name xxx" Error in SharePoint 2010 FBA

I have a SharePoint 2010 web application that I'd like to use a custom membership provider with for authentication in an extended internet zone; however, I end up receiving the following error:

System.ServiceModel.FaultException`1 was unhandled by user code
  Message=Cannot get Membership Provider with name xxx. The membership provider 
  for this process was not properly configured. You must configure the membership 
    provider in the .config file for every SharePoint process.
  Source=Microsoft.IdentityModel
Action=http://schemas.microsoft.com/net/2005/12/windowscommunicationfoundation/dispatcher/fault
  StackTrace:
       at Microsoft.IdentityModel.Protocols.WSTrust.WSTrustChannel.ReadResponse(Message response)
       at     Microsoft.IdentityModel.Protocols.WSTrust.WSTrustChannel.Issue(RequestSecurityToken rst, RequestSecurityTokenResponse& rstr)
       at     Microsoft.IdentityModel.Protocols.WSTrust.WSTrustChannel.Issue(RequestSecurityToken rst)
       at Microsoft.SharePoint.SPSecurityContext.SecurityTokenForContext(Uri context, Boolean bearerToken, SecurityToken onBehalfOf, SecurityToken actAs, SecurityToken delegateTo)
   at Microsoft.SharePoint.SPSecurityContext.SecurityTokenForFormsAuthentication(Uri context, String membershipProviderName, String roleProviderName, String username, String password)
   at Microsoft.SharePoint.IdentityModel.SPClaimsUtility.AuthenticateFormsUser(Uri context, String userName, String password)
   at Fellowes.Commerce.Site.Layouts.Fellowes.Commerce.Site.Authentication.SignInControl_Authenticate(Object sender, AuthenticateEventArgs e)
   at System.Web.UI.WebControls.Login.AttemptLogin()
   at System.Web.UI.WebControls.Login.OnBubbleEvent(Object source, EventArgs e)
   at System.Web.UI.Control.RaiseBubbleEvent(Object source, EventArgs args)
   at System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler sourceControl, String eventArgument)
   at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
  InnerException:

I have put the membership information in the Default Zone config, the Internet Zone Config, the Token Service config and the Central Administration config, but it is still complaining that I don't have the membership provider in the config for every SharePoint process. Is there another process that I've missed? Everyone else who received this error missed adding the entry in the token service, but I have already added it there. I am stumped!

So it turns out that I didn't have the Claims to Windows Token Service started which is located in Central Administration > Manage Services On Server. Once I turned that on, it started working. Setting up the SQLMembershipProvider as Matt suggested got me pointed in the right direction, but it didn't turn out to the ultimate solution.