Conditional Formatting in Excel

dear all

when am creating Conditional Formatting, am getting one peculiar problem

say my excel file is having data

NA
ERR
100
20
100.20
102

Now with my conditional formatting would like to show as Red color for cell>100 so it should show only 2 cell red color i.e 100.20 & 102

but why NA & ERR is also getting Red color.

please help