Just my two cents worth for what it's worth

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[img]http://forum.aquacomputer.de/index.php?page=Attachment&attachmentID=3959&h=ef6d7886bb891bca330e10035c88851d2f7cc4ca[/img]
In this above pic you posted... It's always been in my experience that the Blue Wire is for RPM readings & the Green wire is for PWM control..
SO!!! If that's the case, you have the pump PWM wire connected to the PA & not the RPM wire... So that would probably explain why the PA is not picking up any RPM signals from it's one wire pin connect plug that your using.
In the above pic your PA is just picking up the PWM wire.. I suggest you might try & swap those green & blue wires around & see what you get then

... Might not work.... But certainly looks a better option than the one you got connected up at the moment..
Good luck
N.