SRM inaccurate readings

JohnCisco10

Not sure if this should go here or in another section, but...

Bought a used SRM, amateur model. Worked just fine on my old bike the first week I had it. Bought a new bike (new Giant TCR advanced) and installed it and on my ride my cadence was nearly double what it actually was and my power reading was off because of this as well.
I've tried positioning the power sensor everywhere I can (i'm using double sided tape to secure it) and I have some interesting readings now. If the sensor is positioned on the downtube, my cadence when pedaling forward is roughly double actual, when I pedal BACKWARDS it is fine. If I position the sensor on the chain stay behind the BB the cadence is fine when pedalling forward but about double when pedaling backwards. Power appears to be off still and also sparadically get readings of 0 on cadence and power. I've read the SRM manual about 5 times over and tried finding any info online but for the life of me I can't seem to get this positioned properly. Either that or maybe the hardware in the cranks is bad???

I contacted SRM and they told me to keep trying to reposition the sensor and if I can't get it to work to send it in. Since the only thing I've done differently is put it on a different bike, I'm so far reluctant to think the unit is bad.

I have not yet put it back on my old bike but maybe that's the next step?

The new Giants, the BB area of the frame is absolutely huge and has different geometry than my Orbea, which is making mounting the sensor difficult. With the crank off, and I run the sensor over it, the cadence appears to be fine and not wacky.

help!

John