Hi Sel,
If you are intending to back-test with tick data then you will need to successfully launch MT4 via Tickstory. In some cases MT4 takes some time to load which might generate this error. If so, try selecting the ‘launch’ option again once MT4 has fully started and see if this works (you will know when you get 99.9% back-test results).
If this is still giving you problems, the next best bet is to try Birt’s TDS: http://cd710nh5qn5ax84ol4ncpnfp99.hop.clickbank.net/ (Note: Affiliate link).
Hope this helps.