Unfortunately, at this stage, the DPD and bpost module both load a Google maps api, DPD loads later (comes later in alphabet) so overwrites the bpost gmapsapi code breaking the module.This is not a bug neither on bpost nor DPD module but let's say an integration issue.
You would like to work with both bpost and DPD on your Magento Webshop ?
Don't worry, a workaround has already been developed. Please visit
for more technical informations.