Quote from PointOne:
ES_FUT_200706_GLOBEX_USD
YM_FUT_200706_ECBOT_USD
This also works for any IB ticker:
SGXNK_FUT_200706_SGX_JPY
You should have already allowed for DDE and ActiveX under the Configure-API menu on TWS.
I assume you do fill in cell B2 with your userid (the same as the login for TWS) and have just blanked it out for posting here?
Open the worksheet with macros disabled, don't update values, make these changes then save, then reload and let the macros run and allow updates. The first time you load with new tickers leave it alone for at least 5 minutes to run through one whole bar (the next time you open it should work fine).