I have a string attribute to simulate a floating type (unfortunately, not using 4.0.1 yet).

I have a string custom attribute, and now trying to add a validation using a regular expression.
This field has to contain a number in the 0-100 range, without decimals, or if decimals, up to tenth (up to 2 decimals only).

My expression is:
(100)|(\d{1,2})|(\d{1,2}[.]\d{1,2})
although I also tried
(100)|(\d{1,2})|(\d{1,2}\.\d{1,2})

which works fine in the sample text box, but within a workitem (either Eclipse or Web, let's say at "execution" time), the behavior is not the same, and it does not accept numbers with decimals.
What am I doing wrong?
--Claudia