Error message – current settings appear to be invalid

I’m using this plug in one two sites, and both are showing a message that says current settings appear to be invalid – but I’m not sure why. Can anyone help?

This is for MMM site –
2-allowed retries
720-minutes lockout (12 hrs)
2 -lockouts increase lockout time to 48 hours
24 – hours until retries are reset

Current setting appears to be invalid. Please make sure it is correct. Further information can be found here

And for my SSE site –

218 lockouts since last reset
173 IP is currently blocked from trying to log in

2 – allowed retries
720 -minutes lockout
2 – lock outs increase lockout time to 48 -hours
49 – hours until retries are reset

As you can see my second site is currently under attack and I’ve locked out 173 Ip addresses in the last hour alone. Thats why its really important my settings are correct and this is working properly!

Can anyone help? Why are my settings invalid.
And does anyone have any suggestions how I can protect my sites – this is VERY worrying!

Thanks

http://wordpress.org/extend/plugins/limit-login-attempts/