Animation is not rendering

[Mogno]

I'm having trouble rendering certain animations in Mandelbulb 3D 1.8.9
The preview animation looks fine but when I hit the final render button only a single image is rendered & is continuously replaced by the next rendered frame. But the Zdepth files render as a sequence as it should.
I'v a number of projects with different equations ready but cannot ever render an animation because of this problem. 
Any help please ?

[m2001]

if u upload the .m3a i could test.

The "Increment" value is =1 one 

and ... i would install a second instance

[Mogno]

Thanks. Here's the m3a.
Let me know if I've set something wrong.

http://www.mediafire.com/download/d4hdamzyztnmfw7/T3_1.1.m3a