Cake Flour Substitute

From the Zaar, recipe number 87689. I think Erin's had some success with this one but I have to tell you that it caused me some serious problems with Cathey's cake. I ran out of the Bulk Barn cake flour and thought I'd give it a whack. I ended up having to add at least another half cup of milk and two or three extra egg whites to get the consistency to where I was used to it.

I might not have noticed if I hadn't made that white cake recipe roughly a dozen times in the last two weeks (it feels like). I don't know if it would have been a problem if I had done it by weight though because I suspect that my flour is wicked dry. I don't think I want to try it again though because that's just more stress than I needed right before that cake was due because the first one fell apart and I was seriously running out of time for the base cake at that point.

Erin, did you try it with a cake that you had made with regular cake flour previously?