Error 0xc02020a1: Data Flow Task: Data conversion failed. The data conversion for column "Column 1" returned status value 4 and status text "Text was truncated or one or more characters had no match in the target code page.".

I have a a table which has a column:

material_desc nvarchar(255)

I am loading data using SSMS import from a csv file. While laolding a line:

Concentrate of Poppy Straw (Material Specification Name)

I get error:

Error 0xc02020a1: Data Flow Task: Data conversion failed. The data conversion for column "Column 1" returned status value 4 and status text "Text was truncated or one or more characters had no match in the target code page.".

I though this error was because 255 size  in nvarchar is 255, so I increased it to 1024, but I still got this error. I do not think error is because size of my column is small; it has to do something else.  I changes Specification Name to Sprec Name, then row was loaded.

I come from Oracle background. I fail to understand reasons for trunction; is there some option to be set, but import wizard does not provide any options.  Will appreciate your help.