I can't see anything explicitly stating the support of a CAST. What are you trying to accomplish? Just curious, maybe there's another way tdanner might be able to point out for you. Or at least confirm..
I actually try to plot undp poller output in custom chart but datatype of status in custompollerstatus table defined as string type but i need to convert/cast the data as Int type so that i can plot data on chart and analysis the trend of voice traffic.