DSXchange

I'm getting a fatal error message-
" Internal Error: (types.hasField(fieldSel)): genericUpdate.C:294
Traceback: Could not obtain stack trace; check that 'dbx' and 'sed' are installed and on your PATH"

Can anyone pls tell me what the possible causes could be.The misleading part is that,I've been doing the same operations several times,but this error has never been there.
Thx

Error messgage tells that PATH environment variable (which is set up in the $DSHOME/dsenv file) does not include the directory in which either or both of sed or dbx commands is found.

Check it out for the PATH variable and the files in appropriate path. If that is not there

I've checked that and its there.can there be any other cause?
Thx