Can not auto scale a photograph

Hi Everyone,

I am slowly getting to grips with Solidworks and have created some useful models which all been machines successfully for my model railway.

I now want to create the station buildings and using a series of photographs I would like to create 3d models that I can print.

I know the following which works.
Create new part.
Create the Front Plane to work off.
Open the Tools Drop Down Menu.
Go to Sketch Tools
Go Sketch Picture
Retreive the picture so that it loads into Soliworks Window.
Zoom so the whole picture is in the window.
The picture is successfully loaded.

The problem starts from here.

The picture has Solidworks auto scaler where you can drag each end of the blue dashed line to the positions I want.
When I try to click onto either end it will not shorten or extend the line as required. The picture moves only. If I lock the picture position then I loose the auto scaling feature.

Can anyone help me to do this as I have a large collection of Photos that I need to work through.

The only recent thing I have done is to follow update requirements by Solidworks

Regards

Mike