The issue appears to be that the dates/times are correctly formatted for the function. There are several ways they can be formated. If you look in the documentation for TradingChart[], you will see this documented under "Details and Options" in the documentation for DateListPlot.

The most concrete and precise way you can specify the date is using a list of numeric values: {y,m,d,h,m,s} (year, month, day, hour ....etc). I would reccomend doing this.

How are you choosing to give your dates to TradingChart or DateListPlot? You may want to check the documentation to see if it is an accepted way of specifying the date. If not, try specifying it using a list as mentioned above.