IDOC_INBOUND_FROM_FILE

hi,

i'm using IDOC_INBOUND_FROM_FILE to read the content of text file, then i want to convert it into idoc.

for that i have created one file port using we21.

But while i'm executing IDOC_INBOUND_FROM_FILE (by giving filepath and port)system is telling error in opening file.

can anyone help me......this is vey urgent