ur format should be like this
ACC,20141201,09:17,1472.75,1476.90,1472.20,1474.50,2441 [missing time component]
Ticker, YMD, Time,Open,High,Low, Close,Volume
in default format ur missing the time component - so invalid date format/value
define the format in this way and save it , so that u can use this format for subsequent uses.
rgds