how to import different background images in different levels with exact overlapping

[santbose]

I have four different images of a design as follows:

1. basement
2. ground floor
3. first floor
4. roofing

I imported the basement background image with 150m in length of drawn line and origin of the image as X:0.00 and Y:0.00 in my basement level.
Then I imported the ground floor background image in my ground floor level with the same values, but there was a lot of difference and both the images did not overlap. I could understand this as I had already drawn the walls of the basement.

Can anyone help me out in this please. Thanks in advance.

Santbose