At least one space-time cube provided in the Input Forecast Space Time Cubes parameter was created using a different Number of Time Steps to Exclude for Validation value than another cube. The number of time steps excluded for validation must be the same for each input space-time cube.
The number of time steps excluded in each model is listed in the message. This error also occurs when all input space-time cubes do not exclude any time steps for validation.
Remove any cubes that do not exclude the same number of time steps for validation as the other cubes. Alternatively, uncheck the Evaluate Using Validation Results parameter so that validation results are not used.