Annotate scaling

I'm using LT 2012.

I have a model drawn at 1:1.

I have a viewport set at 1:1.

I use "Annotate | Dimension | Linear" and before I click on the second point the hover text reads the correct value, but when I click the second point the dimension text reads half that value.

EG I draw two objects 25mm apart. I click on the right corner of one and then prepare to clcik on the left corner of the second - the hover text reads 25.0000. But when I click the second corner, the placed text reads 12.5.

How do I make it 1:1?