POSTing valid datetime value causes complicated error

Hi, I have a webservice where i have an entity with property like below:

the abap field data element is GBDAT of data type DATS.

When i send the date using the following function:

getODataDateFromDatePicker: function(datePickerInstance) {  var yyyymmdd = datePickerInstance.getProperty('yyyymmdd');  var splitDateArray = yyyymmdd.match(/(\d{4})(\d{2})(\d{2})/);  var yyyySlashMMSlashDD = splitDateArray[1] + '/' + splitDateArray[2] + '/' + splitDateArray[3];  var jsDateObject = new Date(yyyySlashMMSlashDD);  return jsDateObject;  },

OR

if i just send it like yyyy-mm-ddT00:00:00 for ex: Born: "1990-12-05T00:00:00" the result is the same error as shown bellow:

Call of the method CONV_DATE_EXT_TO_INT of the class CL_ABAP_DATFM failed; wrong type for parameter IM_DATEXT

I also tried sending null, but got the same error even thought i checked Nullable in gateway.

Plz help...been at this for 2 weeks straight now.