OP7 comms to S7 400

I have a problem getting comms between a Siemens OP7 HMI and S7 400 CPU. When I connect it via MPI it works fine, but when I try to connect if via profibus, the OP panel just keeps rebooting.(It does not come up with the message that it can't connect to the specified address). I did a test with a S7 300 315-2DP CPU and then it works fine via profibus. Anybody come across same problem?

Can't say I've seen that but then again I have not set one up from scratch. On my current project we have literally 100's of OP7's connected to S7 400's.

One thing in common, they are all integrated in their respective projects and can be seen in netpro as part of the network.

Thanks PeterW
I came right. The integrated OP7 config. in the project was different to the OP7 config. That caused a bus problem and I believe the OP7 reboots to try and establish comms again.
Regards