question about Romanian accounting rules

Hello, I am working in a french company and we would like to receive an employee from a Romanian company in our company during a 3 month period. We are taking in charge everything, transport costs, accomodation etc. But for the other expenses we need the Romanian company to make us an innvoice for putting their staff at our disposal. So that we will pay them. They say that according to the Romanian accountancy it is not possible for them to make an invoice, as this activity is not included in their list of activities. Is it true that according to the Romanian accounting rules a company doesn\'t have the right to invoice to another company expenses for putting staff at their disposal? Thank you in advance, if you could me give an advice.