Some NRF24L01 modules not working

Dear Robin2,
I tried it. But It were this messages.

SimpleTx Starting
Data Sent Message 0 Tx failed
Data Sent Message 0 Tx failed
Data Sent Message 0 Tx failed
Data Sent Message 0 Tx failed
...

And this on the receiver:

SimpleRx Starting
Data received Message 0
Data received Message 0
Data received Message 0
Data received Message 0

No errors other wise. Please help.

Hemantha