I found a bug using OSG and dae-writer plugin that uses COLLADA DOM.
The problem: Textures are often written without paths, e.g. only filename without folders.
Closer investigation showed that if the output_file_name.dae already exists, the path is, for some reason, written correctly. But if the output_file_name.dae does not exists (it is not overwritten), the path is missing. Only texture file names are written.
Investigation proved, that even fake empty output_file_name.dae is enough for COLLADA, to work correctly.
I eliminated all other possible sources (like existence or non existence of texture files), and it seems like the bug is in COLLADA DOM or in OSG collada writer.