Signature validation using signatureValidate

Hi,

We have designed a form where we use signatureValidate to check the validity of a signature. It has been working fine until recently where we all of a sudden get this error when calling the function:

          TypeError: oField.signatureValidate is not a function

This is the code that we use when validating the signature:

          function validateSignatur(){

               var iResultat;

               var sBesked = "";

               var felt1 = form1.side1.sub_Underskrift.fld_Underskrift.somExpression;

               var oField = event.target.getField(felt1);

               var iStatus = oField.signatureValidate();

               var oSigInfo = oField.signatureInfo();

               sBesked = oSigInfo.statusText;

               iResultat = iStatus;

               return iResultat;

          }

As I said earlier this has worked fine for some time now, but recently is has stopped working. Is the signatureValidate function no longer supported or what could the problem be??

/Caspar