This could be related to the caregiver's cellular provider location services and/or the client's location in regard to cellular towers.  

You can try to extend the distance range in the Office Settings Main Tab to see if that resolves it.  

You should check the map in the client profile, and make sure that the "pin" is in the correct location. If it isn't, you can click on it and drag it to where it should be.

If the problem is client-specific, you can exempt that particular client from the range requirement.  

You can also have the caregiver dial in from the IVR system to perform the clock in/out using either the client's phone or the caregiver's phone.  Make sure that the phone is tagged as "time tracking", and the client profile allows clock in/out from the caregiver mobile.