LSMW-Error Msg:No target structure could be found

hello friends,

I was trying to upload data for 0000.0001,0002 using LSMW, 

first 3 steps are recorded, but when i reach the the 4th step , m getting an error msg :<u><i><b>No target structure could be found.</b></i></u>could u plz suggest y this error is coming and where to maintain the target structure.

many thanks

desia