--- trunk/mdtools/interface_implementation/TraPPE_ExFF.cpp	2002/10/16 20:01:53	136
+++ trunk/mdtools/interface_implementation/TraPPE_ExFF.cpp	2002/10/16 20:02:05	137
@@ -18,8 +18,10 @@ TraPPE_ExFF::TraPPE_ExFF(){
 
   // generate the force file name
 
+  
   strcpy( fileName, "TraPPE_Ex.frc" ); 
-
+    fprintf( stderr,"Trying to open %s\n", fileName );
+  
   // attempt to open the file in the current directory first.
   
   frcFile = fopen( fileName, "r" );
@@ -29,6 +31,16 @@ TraPPE_ExFF::TraPPE_ExFF(){
     // next see if the force path enviorment variable is set
     
     ffPath = getenv( ffPath_env );
+    if( ffPath == NULL ) {
+      fprintf( stderr,
+	       "Error opening the force field parameter file: %s\n"
+	       "Have you tried setting the FORCE_PARAM_PATH environment "
+	       "vairable?\n",
+	       fileName );
+      exit( 8 );
+    }
+
+
     strcpy( temp, ffPath );
     strcat( temp, "/" );
     strcat( temp, fileName );