Import blender ’merged’ models (convert blender to j30)

Hi folks, I tried merging some models in blender (using ctrl-j).

I saw after that the initial attempt (ctrl-j) pulled in multiple textures/materials - that the import failed

I tried again, after deleting all materials/textures, and creating a new shadeless material for the newly created merged object, but now when I try in import I get …

Child (framework_edge1) attached to this node (TableRightBackChunk)

TableRightBackChunk: (10.016685, 1.5072843, 10.505829)–> null

Child (TableRightBackChunk) attached to this node (Models/cleanTest4e.blend)

Loading obejct: topDisplay

Importing mesh.

Loading material.

Materials name: {0}

Trying to write asset failed, asset data null!

Import failed?

any thoughts or pointers?