Assigning metadata column type value from one list to another list giving null value exception.

i am assigning value to a Managed metada column from a  Managed metada column in a  list to another list using the following code

item["Location"] = CurrentListItem["Location"].ToString();

The code works fine for other metadata columns in my list, But for Location metadata  column if CurrentListItem doesnt have any value it throws null value exception but same works fine with other metadata column in my list even if it doesnt have any value.Any pointers on how to solve the issue will be helpful.