Passing text via WebRFC 'wrinkle'

We have written a an ABAP function module that returns material sales text on entry of a material code. This works well in most situations but it seems to throw an error if the sales text string ends in '....' as in ' please type in the rest of your message here ....'

This is the output string from the FM when run from a browser ...

{"results": [ {"key": "mat_no", "value": "COMSALE1 "}, {"key": "sales_text", "value": "Commission for negotiating the sale, the sum of £..."}, {"key": "error_code", "value": "0"}]}

The same input parameters from Personas gives me the script failed message - 'Calling the given RFC failed'.

Any feedback much appreciated.

Thanks.

Patrick.