That looks about right, though the spelling on the ending parameter is different than in your query. Does this work?

Dsum1: Round(DSum("[Log]","[Data]","[TradeDate]<=#" & [TradeDate] & "# AND TradeDate >=#" & [Enter Starting Date] & "# AND TradeDate <=#" & [Enter Ending Date] & "#"),9)

Glancing at the records in the sample, it appears to. Frankly, given the first criteria it shouldn't be summing data beyond the TradeDate anyway.