DSXchange

I'm getting a strange error which i dint meet earlier in any of my projects. I tried to combine two sets of huge volume of datasets holding a different xml connected by a same ID. When combine those two into one datasets, i'm getting an transcoding error
(XEF) message.
Can any one please help if you have faced the similar kinda issue.

Note: Proper nls mapping are handled. UTF8.

Post the complete, unedited error message.