VNAV disengaging to pitch mode

[Mephic 129]

I have following issue: 

 

I'm in cruise, my route has no link-type issues, it's downloaded from SimBrief. I choose a point to which I want to descend in VNAV. I wait until I'm 2 nm out of TOD, I press Vnav it activates in white. Alt sel on. Altitude set properly. At TOD aircraft starts to descend, 5 seconds after it switches VNAV off and enters pitch mode. 

What the...? 

EDIT: FIXED

 

Reason was simple, Mephic, who is a complete utter idiot, was pressing VTO instead of entering appropriate waypoint as "TO" in VNAV screen. 

 

Thank you, I will be learning something new every day with this amazing bird  

[Airbrnetravel 0]

Lol well thanks for posting back I'm sure we've all done that.