The jQueryUI slider expects int values, not string values. val()
returns strings.
If you do this it fixes your issues...
var getmin = parseInt($('.getmin').val(), 10);
var getmax = parseInt($('.getmax').val(), 10);
You'll also have to handle NaN values, so you could also do this...
var getmin = parseInt($('.getmin').val(), 10);
var getmax = parseInt($('.getmax').val(), 10);
if (isNaN(getmin)) getmin = 1;
if (isNaN(getmax)) getmax = 10;
(assuming 1 & 10 are your default values).