[jQuery] issue with ajax function

[graphicsxp]

Hi,

I'm trying to send a string to my webservice. The method I call
expects a string parameter and returns a string of JSON data.

I've tried this way :

 $.ajax({
          url: "Publication.asmx/GetPublication",
          data: "pText=some text",
          type: "POST",
          contentType: "application/json; charset=utf-8",
          dataType: "json",
});

in which case I get the following error and the webservice is not even
reached :

Invalid JSON primitive: pText

and this way :

 $.ajax({
          url: "Publication.asmx/GetPublication",
          data: "pText=some text",
          type: "POST",
          dataType: "json",
});

in which case the webservice is reached but then when the ajax call
returns I get the following error :

parseerror

What do i need to do to fix this ?

Thanks