Objects in groups don't line up?

Anyone seen something like this before? Two rectangles in two separate groups. The groups should be lined up horizontally, but if I add a line “l1”, they don’t line up any more?!?

Or am I wrong in how to use groups?

– two groups
g0 = display.newGroup()
g1 = display.newGroup()

– both with boxes
r0 = display.newRect(g0, 0, 0, 100, 100)
r1 = display.newRect(g1, 0, 0, 100, 100)
r0:setReferencePoint(display.TopLeftReferencePoint)
r1:setReferencePoint(display.TopLeftReferencePoint)
r0:setFillColor(255, 255, 255)
r1:setFillColor(255, 255, 255)

– g1 has a line
l1 = display.newLine(g1, 0, 50, 100, 50)
l1:setColor(255, 0, 0)
l1:setReferencePoint(display.TopLeftReferencePoint)

– line g0 and g1 up on the screen
g0:setReferencePoint(display.TopLeftReferencePoint)
g1:setReferencePoint(display.TopLeftReferencePoint)

g0.x = 100
g0.y = 100
g1.x = 100
g1.y = 200
[import]uid: 138193 topic_id: 25851 reply_id: 325851[/import]