These errors indicate that for the date range chosen the instruments do not have full data. For example, if the scan start date was 2000 a “Bad Data” error means the symbol in question started trading after 2000.
There may also be symbols that have stopped trading due to acquisition or delisting during the data range requested.
Finally, there are cases where although a symbol has traded the full range at some point there was a corporate event that fundamentally changed its capital structure – a merger of different classes of shares for example. When this happens it will generally not be reflected in a free feed like Yahoo! or Google. But IQ will usually carry its price only from the date of the change in structure.
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