I get that, but as in your other static addressed IP's delivered by DHCP, they must not be within the range that you have set.
Look at your LAN tab the left hand Range box will have an IP if 10.0.0.x, where x is something greater than 52, probably 100.
The DHCP range is a subset of the full range and does not cover the statics that you have added the bottom.
You have selected the full range at the top of the page, 10.101.0.1 - 10.101.0.254, so you can't add ANY static's to that network. Reduce the range at the top of the page so there is space for the static address 10.101.0.2.
Change the left hand range box to '10.101.0.x' where 'x' is anything greater than '2' i.e. 3,4,5 etc. you can leave the top end if you wish at 10.101.0.254.
Then there will be room for 10.101.0.2.
I think one of us is having a bad day, eh?