Here is the offical explanation of your error:
The requested number of buffers or the buffer size is not allowed. For example, the buffer limit for Lab and 1200 devices is 64K samples, or the board does not support multiple buffers.
You can also find this information in the NI-DAQ Help file. It gives a list of all error codes and their explanation. There is a Knowledge Base on National Instruments' website entitled
I Get Error -10026 which discusses this error and the limits for an E-Series Board.
J.R. Allen