poloniex API request BUY SELL CANCEL cause error = "Invalid API key/secret pair."; - api

Question

Hello To every one I am writing in swift 3 trading app. I have problem only with 3 commands buy sell and cancel , that ones cause error = "Invalid API key/secret pair."; others like returnOpenOrders , returnTradehistory returnBalances works fine and returns proper values.
That is may request function :
func getRawJSON(paramss:[String : Any]){
var paramss1:[String:Any] = [:]
let APIURL = "https://poloniex.com/tradingApi"
let timeNowInt = Int(NSDate().timeIntervalSince1970 ) * 10000000
var zdanie2:String! = ""
for (x,y) in paramss{
paramss1[x]=y
}
paramss1["nonce"]=timeNowInt
for (x,y) in paramss{
if (zdanie2 == "")
{zdanie2="\(x)=\(y)"
}
else
{
zdanie2=zdanie2+"&"+"\(x)=\(y)"
}
}
zdanie2=zdanie2+"&nonce=\(timeNowInt)"
let array: [UInt8] = Array(zdanie2.utf8)
let hmac: Array<UInt8> = try! HMAC(key: secretKey!.utf8.map({$0}), variant: .sha512).authenticate(array)
let hmacData = Data(bytes: hmac).toHexString()
let headers = ["Key": publicKey!,"Sign": hmacData] as [String : String]
request(APIURL,method: .post,parameters: paramss1,headers:headers).responseJSON {
response in
print(response)
print(response.request)
}
}
Here is my buy/sell function :
func buy(currencyPair:String,rate:Double,amount:Double){
return self.getRawJSON( paramss: ["command":"buy","currencyPair":currencyPair,"rate":rate ,"amount":amount])
}
func sell(currencyPair:String,rate:Double,amount:Double){
return self.getRawJSON( paramss: ["command":"sell","currencyPair":currencyPair,"rate": rate ,"amount":amount])
}
The output from headers parameters(var paramss1 ) is :
["amount": 2.0, "command": "sell", "nonce": 15308121310000000, "currencyPair": "BTC_XRP", "rate": 7.6000000000000004e-05]
The array for sign is :
amount=2.0&command=sell&currencyPair=BTC_XRP&rate=7.6e-05&nonce=15308121310000000
I really dont know what is wrong
Can you help with this problem ??

Answer 1

rate value is invalid.
rate and amount values must be like 1, 1.1, 1.00000001.
Invalid request:
amount=2.0&command=sell&currencyPair=BTC_XRP&rate=7.6e-05&nonce=15308121310000000
Valid request:
command=sell&amount=2.0&&currencyPair=BTC_XRP&rate=7.000006&nonce=15308121310000000