There is a rule about uploading X files and not DBO files, but that only really relates to store items, free items can be whatever you like as long as they work in GameGuru.
However as a rule of thumb it's usually best to provide the .x file and not the .dbo file, this is because the .dbo file isn't a real model, it's kind of a basic clone of the model that GameGuru has configured to the copy of GameGuru it was created on.
Also, your upload is incomplete, it does not contain a texture file, and the FPE line points to your own PC for the texture (textured = c:/Users/Tim/Pictures/wood-textures-high-quality-) you need to provide the texture in the zip and change that line to the name of the texture.
Another rule of thumb (although not necessary, just better), try to provide textures in .dds (compression 1) format, the reason for this is because GameGuru allows for normal, specular, and illumination maps, but only in .dds format. They should be named:
nameoftexture_D.dds (this is your base diffuse texture)
nameoftexture_N.dds (this is your normal map texture)
nameoftexture_S.dds (this is your specular map texture)
nameoftexture_I.dds (this is your illumination map texture)
With the "textured" line in the FPE being
textured = nameoftexture_D.dds
(it only needs to have the diffuse texture listed in the FPE as it automatically find the N, S, and I maps from their names)
The tips I list here aren't all 100% required, but they do all help to make the models a lot more compatible with GameGuru.
i5, NV960 2GB, 16GB memory, 2x 2TB Hybrid, Win10.
i3 , Intel integrated graphics, 6GB memory, 512GB Generic SATAIII Win8.1.
Intel Celeron (duel Core), Radeon integrated graphics, 4GB memory, 180gB Generic SATAII, WinVista.
Q6600, Intel integrated graphics, 8GB memory, 512GB Generic SATAII, Win7.
