On going Transmission problem for E430

Question

2002 E430, went into limp mode and no gear was showing on the dash
checked 13 pin connector it was dry no sign of oil leak.
transmission oil is on full
I fitted a used Floor shifter , the dash now displays the gear but none of the gears engage.
What is next please ?
Just ordered a iCarsoft MBII for Mercedes Benz/Sprinter/Smart Professional Diagnostic Tool Scanner
for good measure.