it really works:
When running an interactive report you may encounter the following error message:
"An internal error occured while calling 'processDPCommands' API (Error: ERR_WIS_30270)"
This message will appear if your server is running out of memory, especially if the LMS, the databases and Business Objects are all installed on the same server.
To free up your server memory we recommend that you turn off real-time caching in Business Objects as follows:
1. Log into the Business Objects CMC
2. Go to the 'Servers' area of the CMC
3. Double-click on the WebIntelligenceProcessingServer server to open the properties
4. Scroll down the page and uncheck the 'Enable Real-time Cache' checkbox
5. Click 'Save and Close'
6. Highlight the WebIntelligenceProcessingServer server which should now have a flag next to it
7. Right-click and select 'Restart server' for the change to take effect
Your server will now have memory available to it and you should find that the error message will not be shown.
As Mark said, it could be a Prompt or Filter error.
There need not be a particular prompt issue per se but the underlying cause could be that you changed the datatype of a universe object in the Universe.
Now unless you change the value in the Filter that you have used, to the new/correct datatype, you will get this issue.
I suggest you open the Edit Query box and check all your report filters for correctness w.r.t the Universe Objects.