List Data Validation still fails for document library when data is valid

This has been bugging me for a whole day! I have a document library with a column with Column Validation.

Whenever i try to add a file to the document library, it fails even when the data input is valid!!

                    try
                    {
                        file = listFolder.Files.Add(destFile, binFile, false); //this line throws error regardless of whether data is valid or not
                    }
                    catch (SPException listException)
                    {
                    }