We encountered this known issue with DTS and Excel today. Instead of importing the model for cars with purely numeric models, like the 206, it imported NULLs. After a lot of searching, we found some really useful information and with this, and a bit of investigation I worked it out.

As they say, select to Disconnected Edit the DTS package, selecct the Excel Connection and expand the OLD DB properties. In there is a property "Extender Properties". Select this, and in the right hand pane update the Value to have IMEX=1.