fading in an object

I want to fade in an object during an animation. the object overlaps some other objects which are not faded in.
I tried a lot of things, but I cant make it work!
the object has a simple color material with some reflectance and specularity.
I generated an IPO for the alpha value and let it go from 0 to 1,
I also let the IPOs for ref and spec go from 0 to 0.5 each.
I turned on ztransp, radio, traceable and shadbuf.
so at the beginning it is invincible, nice, but after fading in, it is transparent, which i dont want. if i turn off ztransp, the latter problem is resolved, but therefore the object is not invisible at the beginning (instead i see its nonshaded shape). also trzing raytransp instead of ztransp didnt work.
i tried playing with the mode ipo to toggle the ztrans setting during the animation, but frankly i didnt understand how to do this.

has anyone a solution how to resolve this problem? thanks in advance,

I’ve encountered this sort of problem in a fede-out kind of animation, I had problems with visible specularity I solved by setting specColor to black. I actually can’t understand the “after fading in it is transparent” thing. Could you explain further?

You could try scaling it from 0.0 to 1.0. A kind of “grow” in. As long as the axis is in the center of the object it should scale up fine as long as you set linkscale button in them numbers dialog N-Key (3D window)

It is often most expedient to do this sort of thing with render-nodes.

When you do things this way, the object(s) themselves are not affected … only how they are treated in a particular render.

If you find yourself drawing a mental blank when I say “render nodes,” welcome to the wonderful world of Blender! "Yes, Virginia, there is a world beyond ‘that simple little Render button.’ " You need to surf over to the Blender wiki (and of course, elsewhere in this site) and start reading. Yes, Blender does provide “a simple button for your convenience,” but it also provides a world of other possibilities…