lstm预测网格搜索问题

代码：def build_model(optimizer):
grid_model = Sequential()
grid_model.add(LSTM(50,return_sequences=True,input_shape=(30,5)))
grid_model.add(LSTM(50))
grid_model.add(Dropout(0.2))
grid_model.add(Dense(1))

grid_model.compile(loss = 'mse',optimizer = optimizer)
return grid_model

grid_model = KerasRegressor(build_fn=build_model,verbose=1,validation_data=(testX,testY))

parameters = {'batch_size' : [16,20],
'epochs' : [8,10],
'optimizer' : ['adam','Adadelta'] }

grid_search = GridSearchCV(estimator = grid_model,
param_grid = parameters,
cv = 2)
grid_search = grid_search.fit(trainX,trainY,shuffle=False,validation_data=(testX,testY))
my_model=grid_search.best_estimator_.model
prediction=my_model.predict(testX)
问题：RuntimeError: Cannot clone object <tensorflow.python.keras.wrappers.scikit_learn.KerasRegressor object at 0x000002BAB12BA780>, as the constructor either does not set or modifies parameter validation_data