Error after using (keras) and (tensorflow) packages for ANN

Hello guys,
I ran this code in Rstudio

inputs <- layer_input(shape = dim(train_data)[2])
inputs
fit
predictions <- inputs %>% layer_dense(units = 10, activation = "relu") %>% layer_dense(units = 20, activation = "relu") %>% layer_dense(units = 1)
predictions
modelann <- keras_model(inputs = inputs, outputs = predictions)
modelann %>% compile(optimizer = 'rmsprop', loss = "mse", metrics = list("mean_absolute_error"))
modelann %>% fit(train_data, epochs = 100, batch_size = 100)

After running the last line, I got this message:
Error in py_call_impl(callable, dots$args, dots$keywords) :