Using xval with fields containing periods

I have been using xVal with success for a while, but this evening there was a problem where the field containing the period was not validated (client or server). I am using ASP.NET MVC2 and have to use period syntax in cases where I am binding a model to a list. In the example below, I am using a textbox for simplicity:

xVal.AttachValidator(null, { "Fields": [{ "FieldName": "entry[622592].Value", "FieldRules": [{ "RuleName": "Required", "RuleParameters": {}}]}] }, {})


<input type="text" class="text" name="entry[622592].Value"/> 

      

        
        
        
      

    

If I replace both instances of "entry [622592] .Value" with something trivial like "test" then the validation succeeds, but if I leave it that way the validation never fails ...

Has anyone faced this problem? Thanks in advance!