Icom 706 and 6 metres

I use an Icom 706 Mk1 in my car. Coupled to an LDG IT100 auto atu it works well. Press the "Tune" button on the rig and the ATU does its stuff. Although I use mono band whips for the HF mobile the ATU is very useful in broadening the useable bandwidth.  reading the reviews on Eham I recently saw a reference to this mobile antenna  and am thinking about getting one. It seems it is basically a whip with a balun of some sort in the base. Although it would not be likely to be as efficient as a mono band antenna it would, along with the LDG ATU, allow me access to all bands including or so I thought, 50 mhz, 6 metres-a band which I have not used mobile before. 6 metres is output on the same antenna port as HF on the 706
The 706 covers 6 metres as does the LDG atu. BUT as I found out today the 706 will not generate a tuning tone on 6 when you press the tune button. Neither will the atu work on 6 when I generate a carrier from the rig. Why this should be I have no idea. The Specs of the LDG atu state it covers 50 mhz. Now I believe it is a known shortcoming of the MK1 706 that the "tune" button does not work on 6 metres but why the LDG does not react to a  50mhz carrier I am not sure. As it stands though it seems that if I did get the multiband whip I would not be able to use it on 6 metres.