All-zero T maps from first-level analysis in SPM

There are only zero values in my statistical results (T maps) of first-level analysis. I’ve reviewed the beta and contrast maps, and they appear normal.

I’ve re-run all preprocessing steps for this subject, but the all-zero issues persist.

The description in the file header of the spmT files seems unusual:

descrip: 'SPM{T_[0.9]} - contrast 2: effect1'

Is the number 0.9 representing the degrees of freedom for the t-test?

The analysis code for all subjects are the same. And other subjects’ contrast results look fine and even perfect.

Could you experts help me with the all-zero issues?

Thank you very much!