Cause of wobbly slabs

[MissDaisyPants]

Hello, I'm a new poster but a regular on the site...
My dad and I have just laid my Indian Sandstone patio but have a problem with some slabs being loose and/or wobbling. I will rectify this but it would be helpful to know what we are doing wrong in the first place to cause this problem. Is it the bed that they are laid on (5:1 sharp sand -cement mix, between 1 and 2" deep) or is it the fact that stones are so naturally uneven or is it because I didn't point them quickly enough?
Quite a few sound 'hollow' when walking on although we did do a whole bed and not the much despised 5-dab method...
any help would be very much appreciated... I'm going to attack them this afternoon and all weekend.. yes, there are rather a lot!
Thank you!
Daisy

[Tony McC]

The most likely cause is incomplete consolidation - when you tapped down the flags, you did not achieve a full consolidation of the bed, and so, when they are traffiocked at some later time, they are capable of 'sinking' under the additional loading, which is the cause of the dreaded wobble.