Volume offline

[unitech89e9]

My filer is FAS2040 and is data ontap 7.3.6

The I use the filer view to create a volume and set snapshot 10%,

and then I create a LUN almost 90% of volume,

and I miss check the [Space Reserved] check box,

one week ago,the volume become offline,

I check the volume sapce and found it have no any available free space,

So I delete the snapshot and stop all the schedule snapshot!

and reduce the snapshot reserve space frome 10% to 5%,

but when I want to set Space Reserved in the LUN,

It can not let me set,

How can I fix this error?

Can I fix the error through the lun size?