AccountManagerFuture.getResult() results in "Couldn't sign in" screen

I am attempting to use AccountManager to get a token for an installed Google account. When I call getResult() on my AccountManagerFuture object, I get the "Couldn't sign in" screen on the device (which further says, "There was a probem communicating with Google servers. Try again later.). I checked that a network connection is available prior to calling this method. I also checked on the device that I am able to access, e.g. google.com, in the browser. Here is the code for my AccountManagerCallback:

amf = accMgr.getAuthToken(account, authTokenType, null, true,  
    new AccountManagerCallback<Bundle>() {  
        public void run(AccountManagerFuture<Bundle> arg0) {  
            Bundle result;  
            Intent i;  
            String token;  

                try {        
                    result = arg0.getResult();  
                if (result.containsKey(AccountManager.KEY_INTENT)) {  
                     i = (Intent)result.get(AccountManager.KEY_INTENT);  
                     if (i.toString().contains("GrantCredentialsPermissionActivity")) {  
                         // Will have to wait for the user to accept  
                         // the request therefore this will have to  
                         // run in a foreground application  
                         cbt.startActivity(i);  
                     } else {  
                         cbt.startActivity(i);  
                     }

                     token = (String)result.get(AccountManager.KEY_AUTHTOKEN);  

                     } else {  
                         token = (String)result.get(AccountManager.KEY_AUTHTOKEN);       

                     }  
                 } catch (OperationCanceledException e) {  
                     e.printStackTrace();  
                 } catch (AuthenticatorException e) {  
                     e.printStackTrace();  
                 } catch (IOException e) {  
                     e.printStackTrace();  
                 }  

            }  
       }, handler);

Also, these entries in LogCat might be helpful:

08-02 15:51:00.911: I/GLSUser(10134): GLS error: Unknown XXXX@gmail.com com.google
08-02 15:51:00.911: V/GoogleLoginService(10134): Returning error intent with: ComponentInfo{com.google.android.gsf.login/com.google.android.gsf.login.LoginActivity}
08-02 15:51:03.294: I/ActivityManager(324): START {cat=[XXXX@gmail.com] flg=0x10000000 cmp=com.google.android.gsf.login/.LoginActivity (has extras) u=0} from pid 11147

(Note: Actual gmail account name removed to avoid spam.)