Intersection of 2 3D Vectors using equation of line

G'day Excel forum

I'm trying to calculate the coordinates of the intersection of two vectors using the slope and Yint of each coupled with the Easting, Northing and Elevation data, however i can't seem to get the correct Northing.

Would anyone out there be able to tell me where I've gone wrong in the attached spreadsheet? Ive highlighted the issue in pale blue, on each row in the sheet there is a combination of 2 vectors and the associated data for that combination (including slope and y int), I have been able to calculate the Elevation and Easting with ease however the Northing doesn't seem to be working.

P.S. I'm really up the creek on this one, it has been the bane of my existence for quite some time now so any help would be awesome, cheers