Help !!!ORA-06502: PL/SQL: numeric or value error: character to number conversion error

I get this error from the following line... Can anyone tell me why???

colvalue number;
mcn varchar(100);
lotid number;
mrn rowid;

select mcn into colvalue from lotz where lot_id=lotid and rowid=mrn;

I have tried this also

Execute Immediate 'select '||mcn||' into '||colvalue||' from lotz where lot_id='||lotid||' and rowid='||mrn;

Thanks,

JC Received on Tue Mar 28 2006 - 13:50:30 CST