diff --git a/src/gui_qt/fit/fit_parameter.py b/src/gui_qt/fit/fit_parameter.py
index 7426c1b..49568cf 100644
--- a/src/gui_qt/fit/fit_parameter.py
+++ b/src/gui_qt/fit/fit_parameter.py
@@ -237,7 +237,7 @@ class QFitParameterWidget(QtWidgets.QWidget, Ui_FormFit):
 
             for i, (p_i, g) in enumerate(zip(parameter, self.global_parameter)):
                 if isinstance(g, FitModelWidget):
-                    if p_i is None:
+                    if (p_i is None) and (not is_global[i]):
                         # set has no oen value
                         p.append(param_general[i].copy())
                     else:
diff --git a/src/gui_qt/fit/fitwindow.py b/src/gui_qt/fit/fitwindow.py
index 3f9ce48..b93ebec 100644
--- a/src/gui_qt/fit/fitwindow.py
+++ b/src/gui_qt/fit/fitwindow.py
@@ -9,6 +9,7 @@ import numpy as np
 from pyqtgraph import mkPen
 
 from nmreval.fit._meta import MultiModel, ModelFactory
+from nmreval.fit.data import Data
 from nmreval.fit.model import Model
 from nmreval.fit.result import FitResult
 
@@ -419,20 +420,14 @@ class QFitDialog(QtWidgets.QWidget, Ui_FitDialog):
         self.preview_lines = []
 
         for k, model in models_parameters.items():
-            f = model['func']
+            f = Model(model['func'])
             is_complex = self._complex[k]
 
-            parameters = model['parameter']
+            parameters = model['data_parameter']
             color = model['color']
 
-            seen_parameter = []
-
             for p, kwargs in parameters.values():
-                if (p, kwargs) in seen_parameter:
-                    # plot only previews with different parameter
-                    continue
-
-                seen_parameter.append((p, kwargs))
+                print(pp.value for pp in p)
 
                 if is_complex is not None:
                     y = f.func(x, *p, complex_mode=is_complex, **kwargs)