Help in data file

Hi everybody I try to simulate movement water in cnt and I use the data file that I made it by vmd but It gives error and I don’t know why!
And that’s error is:“needed topology not in data file”
Please help me.
Tnx

Hi everybody I try to simulate movement water in cnt and I use the data file
that I made it by vmd but It gives error and I don't know why!
And that's error is:"needed topology not in data file"

that error is due to an incorrectly formatted data file that is
missing information.
consult the documentation for the read_data command to learn about the
file format.

axel.