BluEcho DS will not search for a file if the pathway doesn't point right to it, the devs changed it early DS2 after it used to hang trying to find textures where the creator forgot the " on either end of the pathway, now we have to locate them ourselves or fix the pathways in a text editor.

":runtime:textures::.jpg" << that roughly what you need for a texture pathway (including the " on each end), that way it'll work properly in both DS & Poser.