Trouble modifying diy backdrop

I am trying to put my own .bmp image on kuid:253853:450. I have carefully followed instructions about leaving the picture and alpha file names the same, and staying with 8 bit depth and exact image size. Other than changing to my own kuid, I have not modified any of the other files except the preview.jpg image, and my preview image shows in content manager. My kuid shows faulty: failed to load child images for texture file picture.texture.txt

That .txt file shows the correct file names as the original by Jost62. I don’t intend to upload to DLS because this is only for my use on a layout for me.
I am at a loss as to what is wrong.
I did clone it. I gave the clone a new kuid with my identity. The 3 image files (picture, alpha, preview) are new images I created, but I used those same file names so nothing but the kuid number was changed in the .txt files.
Make sure you use the same names as the file you are replacing.
Since this is a .tga file, you will need to save uncompressed.