Darwin to Lae
Earhart sent wrong frequencies to Lae
"To make sure the message got through, she sent two cables via separate commercial services. Both telegrams expressed the desired radio frequency as wavelength in meters in accordance with the British system. One telegram said that she would be sending and receiving on a wavelength of 36 meters. The second telegram had it that she would be "receiving and transmitting 36.6 meters D-F loop." The message is ambiguous in that the "D-F loop" (the hoop-shaped radio direction finder antenna mounted on the cockpit roof) was a receiving antenna and could not be used for transmitting. Its mention in the telegram implies that Earhart intended to use her direction finder to home in on signals sent by Lae on 36.6 meters."
The two telegrams specify different frequencies. 36 meters is 8.327 MHz while 36.6 meters is 8.191 MHz. Apart from the confusion between the two telegrams, neither one is a frequency on which Earhart could transmit.
Successful communication with Darwin, but not with Lae
"Earhart and Noonan made the twelve-hundred-mile flight from Darwin to Lae without incident except that, once more, there was radio trouble. After takeoff she was able to talk to Darwin for the first part of the journey, but as she approached New Guinea she was unable to establish contact with the airfield at Lae. This time the problem was procedural rather than mechanical. The airline manager at Lae later reported: 'On arrival Miss Earhart pointed out that whereas these radios [the two telegrams she had sent from Darwin the night before] advised us of a wave length of 36 metres, in reality her wave length was 49 metres which explained why we failed to pick up any messages from her.'
"Lae had not heard Earhart’s transmissions because the Lae radio operator had been told to listen on the wrong frequency. But Amelia would not have been able to hear Lae even if the conversion from kilocycles to meters had been correctly computed. In her telegrams she had intended to advise Lae that she would be both transmitting and receiving on her daytime frequency of 6210 kilocycles. For her to receive on that frequency, Lae would, of course, have to be transmitting on that frequency. The radio station at Lae transmitted on 6522 kilocycles, though, and, like most stations at that time, had neither the capability nor the legal latitude to alter its broadcast frequency. Because she did not receive any of Lae’s transmissions, Earhart could not try to use her radio direction finder to navigate. Consequently, she did not discover that her direction finder was unable to home in on high-frequency transmissions."