Canon 5DMk3 will not recognise Speedlite ST-E3-RT

[StuCraw]

Speedlite ST-E3-RT not connecting

I have upgrade my camera software to current version to 1.3.5 and cleared all camera settings.

Cleaned the hotshot of camera and speedlite transmitter, and I still get the on screen message, 'Flash Function settings - This menu cannot be displayed. Incompatible flash or flash's power is turned off.'

1. The transmitter works without issue on Caon 80D

2. Transmitter links without issue to 2 x 600ex-rt speedlites

3. 600ex-rt speedlite works as a master on the 5Dmk3

Any suggestions

[RobertTheFat]

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@StuCraw wrote:

Speedlite ST-E3-RT not connecting

I have upgrade my camera software to current version to 1.3.5 and cleared all camera settings.

Cleaned the hotshot of camera and speedlite transmitter, and I still get the on screen message, 'Flash Function settings - This menu cannot be displayed. Incompatible flash or flash's power is turned off.'

1. The transmitter works without issue on Caon 80D

2. Transmitter links without issue to 2 x 600ex-rt speedlites

3. 600ex-rt speedlite works as a master on the 5Dmk3

Any suggestions

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Speaking from total ignorance, I wonder if the transmitter and the speedlite are failing to agree on the wireless channel to be used.

[StuCraw]

Thanks Bob, but both the transmitter and speedlites are operating in the same channel.

[Tim]

StuCraw, 

We are sorry to hear that the issue persists.  We recommend sending the unit for service at your earliest convenience.  You may fill out an online repair request form at the following link to setup your repair using our online service.

https://www.usa.canon.com/internet/portal/us/home/support/service-repair