I keep hearing the same story. "We bought an ERP system so we're finished with the software debate, right?"
That's a form of denial. The idea of ERP is a grand integrated box of everything you need to run a business. It not only doesn't work, it's not possible for it to work. Three main reasons:
1. Bigger integration means broader audience, which means the added modules are more general. That works for general ledger, but not for much else. Too much of the business process is unique to a business/customer base combination. You need something more specific for order entry, not more general.
2. A very technical point - ERP operates in the frequency domain, the world operates in the time domain. Very difficult to merge the two. For many business operations it's impossible.
3. For the systems that allow you to customize the business process, the assumption is that it's something you will do once, so it's ok to take two years to get it up and running. Exactly the opposite is true. Most businesses are highly dynamic and business process needs to match. Fixed (standardized) process means inability to adapt to change.