Nivled,
Can you give a brief description of your application? Are you trying to synchronize digital input or output on the two boards? Is it a finite or continuous task? Are you using any triggering? This information will help to narrow down the source of the error.
The only other reference I found to error -200288 when writing to the PCI-6534 was the following discussion forum post:
PXI-6534 rewriting IO buffer with DAQmx causes error -200288Again, if you could provide some information about your application, this will definitely help.
Best regards,