problems with eregi on solaris 2.8

Hi, I'm verifying that some user imput is a numeric value and not characters, for that, I have the following lines of code on a script that works fine on php 4.0.1pl2 on madrake linux 7: if (eregi( "([a-z]{11})", $id )==true) return false; but on solaris 2.8 with php 4.0.1pl2 erigi always return false. What could it be? or there's another way to verfy user imput not to be characters and only numbers? I tried is_string function but it didn's work too. Thanks for your answers. -- ------------------------------------- Juan Luis Baptiste M. Ingeniero de Desarrollo SANCHO/BBDO - Nextmedia Interactive http://www.nextmedia-i.com Calle 98 #9-03 Piso 2 Tel: 2 188888 ext. 340 -------------------------------------