The file that you're missing is wooden_wall_short_straight_destroyed_kill_zone_05. CAS

I think you missed a step in your Blue Lotus installation. Did you do this?

4. Download Vercingetorix's PAK extractor tool. http://www.twcenter.net/downloads/db/?act=mod&id=43
5. Copy the contents of the unpaker into Data/packs in your clean version of RTW 1.5.
6. Run the .bat file and let run completely. this may take a while. After its done you'll see a new data folder in the packs directory.
7. CUT or MOVE (not copy) this new Data folder and paste it over the root Data folder allowing it to overwrite everything. NOTE: There should be no Data folder left in Packs.
8. Go back to the packs folder and rename all the pak files remaining (except the patch_0 and patch_1) You can just rename them with a couple of xx in the front ie sprites_1.pak rename to xxsprites_1.pak

The file that you're missing is in the packs folder that you have to extract.