cart-rule disables itself with no reason

[pat123]

when I add a cart-rule (free product) in site http://test.italiaansewijnkopen.be/index.php and order to test this rule he comes with the message that the rule doesn't exist and if I look afterwards at the rule the faction, free product, is disabled. 

When I do this on the other site http://italiaansewijnkopen.be/index.php it works like it should.

Although both sites are created with PS 1.5 and test .italiaansewijnkopen.be is a small copy  having as purpose to test things out before going live.

 

What could be the reason that it works only in one of the sites? I suspect a file which is not the same in both instances , but which ??