Slicer does not recognize .h5 file

I am trying to upload a trained UNet model in .h5 format in 3D slicer, in order to perform segmentation on my ultrasound data. I am using the latest preview release (4.13.0) on my MacBook air. However, I face the error that the UNet model is not selected, although ii have uploaded it.
The error is as below:
Input image: Image_Image

Output image: Prediction

Apply button clicked without UNet model selected

Could you please help me with that?