Search for negative values in view

Search for negative values in view

Hi all,

One of my views shows records from a form that contains one "number" field.
This field is used to imput numbers, which are either positive, or negative. Negative values are entered preceeded by the "-" symbol.

For some reason, in the view that displays those records, all negative values appear alongside the positive ones, but it is impossible to search for the negative values: whenever I input a negative number in the "search" field corresponding to the field, I get an error message "Please enter a valid number to search".

(If I try creating another view, with a negative number set as a selection criterion, corresponding records are displayed, though.)

Where does this come from? How can I arrange it?

Cheers,
D-