Cannot get spot instance prices

[caarlos0]

I'm trying to do basically this:

    client := ec2.New(nil)
    params := &ec2.DescribeSpotPriceHistoryInput{
        InstanceTypes: []*string{
            aws.String("c3.4xlarge"),
        },
        AvailabilityZone: aws.String("us-east-1b"),
        ProductDescriptions: []*string{
            aws.String("Linux/UNIX (Amazon VPC)"),
        },
        MaxResults: aws.Int64(1),
    }
    resp, err := client.DescribeSpotPriceHistory(params)
    if err != nil {
        log.Println(err.Error())
        return err
    }
    for _, pricing := range resp.SpotPriceHistory {
        log.Println(pricing)
    }

But it always fails with:

InvalidParameterValue: Invalid availability zone: [us-east-1b]
    status code: 400, request id: 

I tried several zones and always got this same problem.

What am I doing wrong?

[caarlos0]

Just realized that the client was using another zone, my bad, sorry.