My program:

options noxwait noxsync;
filename patients dde
"excel|D:\lvjinghui\project\pfizer\2010-04-26 A4061039\reference\[A4061039 target and actual graph.xls]1039 !$A$2:$F$68";
data _null_;
   infile patients;
   input;
   put _infile_;
run;
  
Error in log:

ERROR: DDE session not ready.
FATAL: Unrecoverable I/O error detected in the execution of the data step program.
       Aborted during the EXECUTION phase.

请问高手怎样解决这个问题呀？