SMA returns NaN

[vandat1995]

Hi there,
I'm using

const SMA = require('technicalindicators').SMA;
var results = SMA.calculate(input);
But results return NaN; Please help me!
Thanks

with input ;
{
period: 2,
values: [
'31568.07', '32255.56',
'34687.71', '34487.22',
'35911.26', '35031.39',
'33489.96', '33760.94',
'34652.94', '35280.16',
'33672.72', '34206.01',
'33845.64', '32852.04',
'33805.01', '33497.98',
'34253.81', '33070.87',
'32709.09', '32464.46'
]
}

results:
[
NaN, NaN, NaN, NaN, NaN,
NaN, NaN, NaN, NaN, NaN,
NaN, NaN, NaN, NaN, NaN,
NaN, NaN, NaN, NaN
]

[vandat1995]

close my issue, I have not parse input value to number