Question: Finding intersection involving procedure goes wrong

Hello,

Maple_-_Upload.mw

See the upload for my worksheet.

When opened: Combine the first picture with the second picture and you will get the third picture, where the green filled box is a 'safe zone'. Now what I want is to find the intersection between the green line (=0.7) and the red line (the curve), which gave me two answers, as I wanted! No problem at all.

Now when the fourth picture is combined with the fifth picture this results in the sixth picture. So again I tried to find the intersection between the two lines (this time the green line with the blue line; I just name it to be sure that the idea is clear). But this time Maple doesn't give me the points of intersections. How come? I think it has something to do with the procedures, but I can't figure out what it exactly is.

I hope someone can help me out on this.

Thanks,

Frank