diff --git a/Solverz/utilities/io.py b/Solverz/utilities/io.py
index 0823443..ea657cf 100644
--- a/Solverz/utilities/io.py
+++ b/Solverz/utilities/io.py
@@ -31,33 +31,34 @@ def save_result(sol: aesol | daesol, name: str, dir: str = None):
             for j in range(Y.var_size[var]):
                 tempd[var + f'_{j}'] = Y[var][:, j]
             Y_dict[var] = pd.DataFrame(tempd)
-        with pd.ExcelWriter(dir+f'{name}.xlsx', engine='openpyxl') as writer:
+        with pd.ExcelWriter(dir + f'{name}.xlsx', engine='openpyxl') as writer:
             # Write each DataFrame to a different sheet
             T.to_excel(writer, sheet_name='Time')
             for var, df in Y_dict.items():
                 df.to_excel(writer, sheet_name=var)
         if sol.ie is not None:
-            te = pd.DataFrame({'te': sol.te})
-            ie = pd.DataFrame({'ie': sol.ie})
-            ye = sol.ye
-            ye_d = dict()
-            for var in ye.var_list:
-                tempd = dict()
-                for j in range(ye.var_size[var]):
-                    tempd[var + f'_{j}'] = ye[var][:, j]
-                ye_d[var] = pd.DataFrame(tempd)
-            with pd.ExcelWriter(dir+f'event_in_{name}.xlsx', engine='openpyxl') as writer:
-                # Write each DataFrame to a different sheet
-                te.to_excel(writer, sheet_name='Event Time')
-                ie.to_excel(writer, sheet_name='Event Index')
-                for var, df in ye_d.items():
-                    df.to_excel(writer, sheet_name=var)
+            if len(sol.ie) > 0:
+                te = pd.DataFrame({'te': sol.te})
+                ie = pd.DataFrame({'ie': sol.ie})
+                ye = sol.ye
+                ye_d = dict()
+                for var in ye.var_list:
+                    tempd = dict()
+                    for j in range(ye.var_size[var]):
+                        tempd[var + f'_{j}'] = ye[var][:, j]
+                    ye_d[var] = pd.DataFrame(tempd)
+                with pd.ExcelWriter(dir + f'event_in_{name}.xlsx', engine='openpyxl') as writer:
+                    # Write each DataFrame to a different sheet
+                    te.to_excel(writer, sheet_name='Event Time')
+                    ie.to_excel(writer, sheet_name='Event Index')
+                    for var, df in ye_d.items():
+                        df.to_excel(writer, sheet_name=var)
     elif isinstance(sol, aesol):
         y = sol.y
         y_dict = dict()
         for var in y.var_list:
             y_dict[var] = pd.DataFrame({var: y[var]})
-        with pd.ExcelWriter(dir+f'{name}.xlsx', engine='openpyxl') as writer:
+        with pd.ExcelWriter(dir + f'{name}.xlsx', engine='openpyxl') as writer:
             # Write each DataFrame to a different sheet
             for name, df in y_dict.items():
                 df.to_excel(writer, sheet_name=name)