Data Merge - misaligining information

Please help.  I am trying to Data Merge from an excel csv. file into InDesign that i have set up as how i want the final document to look.  I have created the excel file & saved as a .csv, in InDesign i have assigned the fields, but when i hit Preview one of my columns of information from my .csv file goes all over the place - it doesn't just stay in the box that i have assigned it to.