Hi,
this issue can be easily solved in the STEP7. while specifying files there is automatically specified file for imported and converted data with a file name.(lsmw.read and lsmw.conv) . place the cursor on the file name and give delete entry. save and back again goto step7. now the those file will be specified again save and back ..
now read the file and it works perfectly (Y).
this is due to less space in the read file while deleting and assigning it back it recreates so that we have enough space for the reading files .
thanks ,
subramani palani