Column count trips up a lot of people. Column count for a table is very different than column count for a table row. From the docs:
Table Column Count vs Row Column Count
When modifying properties on a section of the Table, always pay attention to which section you selected. Some property names on one section may look similar to properties on a different section. For example, Table Rows have a Column Count property that adds a new column to the row, but the Table Body section also has a Column Count property that will cause the same table to spill out horizontally on the same page. This is great for landscape pages, but on portrait oriented pages it can cause some of the data to be rendered on an unprintable area of the report!