Virtual Machine Manager problem creating a new machine

[TheYikes]

Hello! I'm in bother again. I'm tying to create a virtual machine using Virtual Machine Manager. I go through the usual steps but hwen i click create i get this error:

Unable to complete install: 'XML error: interface type='bridge' requires a 'source' element'

Traceback (most recent call last):
File "/usr/share/virt-manager/virtManager/asyncjob.py", line 72, in cb_wrapper
callback(asyncjob, *args, **kwargs)
File "/usr/share/virt-manager/virtManager/createvm.py", line 2008, in _do_async_install
installer.start_install(guest, meter=meter)
File "/usr/share/virt-manager/virtinst/install/installer.py", line 695, in start_install
domain = self._create_guest(
^^^^^^^^^^^^^^^^^^^
File "/usr/share/virt-manager/virtinst/install/installer.py", line 637, in _create_guest
domain = self.conn.createXML(initial_xml or final_xml, 0)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/lib/python3/dist-packages/libvirt.py", line 4545, in createXML
raise libvirtError('virDomainCreateXML() failed')
libvirt.libvirtError: XML error: interface type='bridge' requires a 'source' element

I've attempted to uninstall it and trying a fresh install but it's giving me the same error regardless.

UPDATE: the problem seems to arise when i select bridged network, i fi select NAT it's fine.