I can see that you're new in here. I really would like to help you but there's nothing I can't do unless you give me something to work with. I can't see your data and just have an idea on what the problem it could be, but it's just a shot in the dark.

Please read the article about Forum Etiquette linked in my signature.

My guess is that there's problem with the data stored in your table (that's why it's a best practice to use the correct data type). Use the queries I gave you to find which are the rows that don't have a valid format.