Texture dissapeared after copying

Hello, professionals, please help me!! I was mapping a cute house with transparent windows, everything was fine. But I copied my house and its windows dissapeared (original's house windows and copied house windows too)!!! But in GZDoomBuilder everything still ok (see screenshots)... O_o I tried every tips I had. Help me!!! I cant do redo, because I did not notice that bug and made too many steps after.

This probably happened because short texture name (like "WALL1") was transformed to full name (like "textures/wall1.png") while copying. This bug is already fixed in the latest revision of GZDB. Zandronum (if you are using it) can't handle long texture names, so check texture names and translate them back to short form.

EDIT: Wait. Judging by screenshots your version of GZDB is ancient, so it doesn't support long texture names. Er... I guess we'll need to see your map.

New experience info: only one name of texture dissapearing (in my case it's "WINDOW1"), if I set another texture (for example defaut "GRASS1") everything is ok. Weird. I dont wanna change my texture's name, "WINDOW1" is perfect =)

Sorry, guys, It was my mistake, I removed S3DUMMY texture from Textures lump in Slade 3. Restoring it solved my problem, thank you everybody