Bathroom lighting and fan query...!!

[Wilko]

Ha ha, my fav is :

A is different from B
Or
A is different to B

Good thing I can add up ok

 

[Midwest]

Still think somehow, you are introducing a voltage at the lights neutral, when turning on the fan. Think you just need to check all your connections are correct.

 

[westward10]

Connect them to the same switch and see what happens.

 

[buzzlightyear]

to an adaptable box (fitted with din rail

loop in from the switchs is better .

 

[mgzr]

Connect them to the same switch and see what happens.

i have double up both switch wires and the fan turns on and off with the switch, but the lighting does nothing....

 

[Wilko]

Guessing from afar, what should be the light neutral is actually connected to the incoming unswitched live.

 

[Richard Burns]

If your connections are correctly positioned then the only thing I can think is to check is that neutral connections on the DIN rail are correctly connected, if one (probably the incoming) were only just in contact then it may not be able to carry the current of both items, however this would be an extraordinarily precise partial disconnection.
I woudl tend to go for a wiring error myself, check continuity when the circuit is dead to see what you get in different switch positions and see if you have continuity along cores between points.