Reporter returns a "httpStatusCode: 400" error when using the date range option.
Date range config is in this format: “dateStart=2011-06-27T00:00:00+09:00&dateEnd=2011-09-11T23:59:59+09:00”

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httpStatusCode: 400
httpMessage: Bad Request
detailedMessage: Invalid value for parameter dateEnd; dateEnd must be a number or ISO 8601 string
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What should I do?

The date and time in Reporter are in ISO 8601 format. Since you are using the web API, you must use percent-encoding in the URI. 
Therefore, “%2b” is the correct URI format, not "+."

Please use the format below.

“dateStart=2011-06-27T00:00:00%2b09:00&dateEnd=2011-09-11T23:59:59%2b09:00.