Messenger ( the green one)

You must explicitly enable Text Message Forwarding for your iPad on your iPhone.

On your iPhone:

Settings > Messages > Text Message Forwarding - set to ON - and explicitly enable your iPad from the list of devices.

Also ensure that Messages in iCloud is enabled on both your iPhone and iPad:

Settings > [Your Name / AppleID] > Messages - set to ON

More information:

How to forward SMS/MMS text messages from your iPhone to your iPad, iPod touch or Mac - Apple Support

Fault finding if needed:

If you can't send or receive messages on your iPhone, iPad, or iPod touch - Apple Support

Hey Jollygirl,

Let's go over this together to see what is going on.

When you Set up Messages on iPad does this article help?

Are you referring to blue (iMessage) or only green messages (SMS)?

Make sure your iPad has been setup to use iMessage.

Cheers.