How could I fix this problem?
Post your entire graph via the camera export in the top right, your dyn file, and an rvt file that we can use it on.
That error means you are feeding the wrong type of data into the node. In this case it’s asking for a polycurve. You’re likely feeding it a curve or a null or other bad data somewhere along the line. Since you only gave us the one sample of the graph we can’t solve it as we can’t see why it’s failing. It would be like asking a doctor to fix your headache by sending them a picture of your foot.
And also show preview of each node.