After Effects -Exporting animated signature to Premiere Pro CS5

Hi everyone, I created a wonderful animated signature in After Effects CS5 and within Premiere Pro CS5 I imported the AE composition and added it to my initial video, but unfortunately while the animation works fine, the signature has a white rectangular back ground which I failed to make it transparent to show the animated signature only over the video. I would appreciate very much helping me to do that task. Thank you in advance. You are great.

I could figure a solution to the problem by adjusting the opacity of the composition in AE, and making some slight editing in Premiere Pro. I may add that I got a better result in achieving my above mentioned target by selecting the opacity blend mode "Linear Burn" and changing the position of the signature under motion effect.

The steps I followed to make the animated signature were as follows:
1) I scanned a handwritten signature and I saved it as a TIF image
2) I imported the above mentioned image in Adobe After Effects
3) I used the pen tool to mask the signature
4) I created a white solid composition
5) I copied the masks to the White solid composition.
6) I copied the white solid masks to a new video composition with same size of my Premiere pro project 1920x1080 and I started to amend the brush size, hardness...etc under stroke
7) I made the end of the stroke feature to be 0% at the start
8) After 3 sec. I made the end comes back to 100%
9) I checked the animation of the signature and it was great, I made the length of the composition becomes 20 sec in length to match the handwriting natural speed
10) I resized the composition to show a size of my signature which does not exceed a 10% of the quarter of the right corner of my video and I selected a transparent background (which did not help in making the rectangle behind the signature transparent), I decreased the opacity to 50% then
11) I opened the Premiere Pro and imported the compostion and I selected the settings I described earlier and at last it worked perfectly.

Dave, you are absolutely right. I missed this crucial setting. With your help I could put back the opacity to 100% and the result is even better. I appreciate your kind help. Many thanks.