have a problem using dht11 sensor!!

i use dht 11 sensor with different sensors(o2, light, dust)

but only dht11 sensor have a problem.

it prints 'nan' .

But sometimes, once about 10 minutes It prints normally 'temperature' and 'humidity' .

Why this problem happen?

use dht11 sensor without any senosrs, it prints well.

please help me

I cannot find your code in the post, maybe you can help? And use code tags! Don't forget the links to the used libraries and to all used hardware.

Do you have a pull-up resistor on the DHT11's data wire?