Working blend modes?

Are there any actual working blend modes in Catalyst? I'm having a massive issue with my contrast/brightness 'dipping' during crossfades. If I was doing this in editing software/photoshop, I'd use something like an additive dissolve or 'add' blend mode.

While I can activate and play with the Catalyst blend modes colour effects, they don't seem to do anything similar to what I'd expect in Photoshop, AE, etc. All of them seem to retain the blacks in an layer (creating a 'dip'), or do something much wierder.

Using custom colourfx presets allows me more control, but since I can't fade their settings, I can't use them in this production. Ditto with mix colourfx.

Am I doing something wrong??

:)