Tronic wireless cycle computer - Error

[stoneywood21]

Spring is just around the corner and I return to a problem which has haunted me for the past two years.
My tronic wireless cycle computer gives an error report as soon as I set it up.
The manual says that this will clear when I move away from a signal source.
But no, I have had the problem cycling through a forrest, without my mobile phone.
This means that wireless is useless. The manufactures have been good, replaced it twice, but without any advice on remedy.
Has anyone else had this problem?
DGB

 

[alda01]

I've had similar issues but never serious enough to require replacement, normally when magnet doesn't pick up on receiver, have you tried running it right past the receiver when not on bike to check it works

 

[alda01]

Have you got a copy of your instructions?