Pink tiles over Orthello 2D transparent tilemap

Hi, I'm using Unity 4 basic and Orthello2D Pro using TILED Tilemap as my level editor. I've built a level editor and exported it to Unity 4 and set it up by using OTTilemap.

The problems is, some of my tiles have transparent part like tables, chairs, cardboards, etc. unlike walls and floors, which has no transparent parts. When I insert the XML and texture to OTTilemap, the transparent part turns to pink colored tiles as seen from this image:

While the view from TILED is correct:

It seems that OTTilemap handles all transparency as 'missing textures'. How to get rid of this issue?

Thx b4