UnPivot Transform -- > Pivot Key value

Is there a maximum string length for the Pivot Key value in an Un-Pivot Transform. I can’t seem to append more than 49 characters, the destination filed is Varchar(Max). If I have a 50 character length string, only 49 are pivoted and appended to the destination table. Anything above 50 characters and the I don’t get any value appended?

Is there a way to set the size of the Pivot Key value in the task, or any way around this issue?

Any help much appreciated?

Thanks in advanceRoy