Q: Combining library (iPhoto) with Aperture

I've just purchased Aperture becasue I saw that I can use the same library that I have with iPhoto as 1 library between the 2.  I also got aperture because of the ability to create different libraries and store them on other drives.  But initially I'm having a problem and I can't understand what the issue is..

First off, I had very little hard drive space left due to an ever growing iphoto library.  So I copied my iphoto library to an external drive set up on my network here at my house (actually its on a timecapsule 2tb).  I then deleted the iphoto library on my macbook air's hard drive and then pointed iphoto to the copied iphoto library.  Iphoto works fine and I can see all my pictures.

Now when I started Aperture, it asked if I wanted to use the existing iphoto library, which I said yes, but it said that the file format was not acceptable.  I'm not sure what the issue is, as I do NOT want to store pics on my macbook air any longer (initially).  What I'd like to do is make an aperture library that I will keep on my macbook air hard drive that contains pics from current travels, and then eventually once they are edited move them to my external drives at my house (either my 4TB networked drive or my 2TB time capsule).

Can someone please tell me if I am or not able to do this?  What could be wrong with my iphoto library that wont allow the 2 programs to use the same library?