Time Machine just does not work!

I have tried to set up, run full backup and then continue running backups at least 3 times for my mabook air and everytime the first backup completes successfully, but then for subsequent backups I get the sparsbindle cannot be accessed error.

I have rund disk utility on the bundle, it’s fine, checked i’m on latest firmware, I am, checked setup and disc permissions, all fine.

Can someone please help or is the duo just not compaptible with time machine (as it is advertised it is?)

Check if the link below helps.