Problem with Georeferencer - turns into black

[geo_exe2000]

Dear all,
since some days I have a problem with the georeferecing tool in QGIS. We use the tool to prepare our high resolution aerial photographies. After the first providing of the aerial photo we normaly correct the resulting image to get a better accuracy. So far so good...

But: If we use the same window again to set more points it sudenly turns into black and the primary foto disappears.

What is wrong? Have you made similar experiences? How may I solve this problem?

Windows XP
QGIS V 1.4.0

Thanks a lot!

Geo.

[Jhelebrant]

Hi,
I always save the referencing points in a file and in case I need to add some points after completed first georeferencing, I always reload the the georeferencer, import the raster again with the points from the first georeferencing and then add the new points.

I assume, that the cause is following:

1) your source file first does not have any ref. points nor world file
2) by first use of Georeferencer, you create points and after running georeferencing, you create world file and load the file in QGIS. In case you use linear transformation, QGIS loads source file and transforms it "on-line", in other cases it saves transformed file as new one.
3) when you have loaded file using linear transformation and use the georeferencer again, it could destroy the world file and so it also changes properties of the loaded file.