Dervied Column Function Error

In the SSIS package i have a derived column with the following expression :

But when i run the package i'm egtting the following error:

[Derived Column [268]] Error: The magnitude of the result of a function call was too big to fit in the result type, and overflowed the type of the operand. An explicit cast to a larger type may be required.

The variable BaseDate has a vlaue of '1/1/1901'. In the flat file i'm having the dates only for the current year. Any suggestion where to look at?

Thanks