The LabVIEW 6.1 Help file indicates that the 14013 error number means "A client's attempt to establish a conversation has failed." Don't know how this relates to your VI. May I suggest using Excel's ActiveX server instead of DDE? There are many, many Excel examples that you can use and/or modify. One example is found under Help >> Examples >> Communication >> ActiveX. You can also go to www.ni.com and do a search for:
+excel +labview +example