cant get top nodal stress for shell 181

hi
When using **nodal_stress()** to get the nodal stress of SHELL181 element, the result is the bottom stress. The top stress cannot be retrieved at all . same for **element_stress()**

code is below

```
rst_path = r"./file-shell.rst"
result = pymapdl_reader.read_binary(rst_path)

result_index = result.nsets-1
print('last set:' , result_index)

nnum, nodal_stress = result.nodal_stress(result_index)
print(nodal_stress)
```

gives
```
[[ -58.35810471 -58.35810471 0. 31.42359352 0.
0. ]
[ -58.35810471 -58.35810471 0. -31.42359352 0.
0. ]
[ -58.35810471 -58.35810471 0. 31.42359352 0.
0. ]
...
[-360.42993164 -177.81101227 0. -43.87812805 0.
0. ]
[-294.92189026 -145.09841919 0. -60.91584587 0.
0. ]
[-211.59954834 -105.04603195 0. -79.2219429 0.
0. ]]
```
shape=(441, 6))
exactly same as bottom nodal stress in apdl results

how can i get both top and bottom nodal stress for the shell element?
thanks. （rst file uploaded）

[file-shell.zip](https://github.com/user-attachments/files/25623172/file-shell.zip)

Start by reproducing the reported behavior with the uploaded file-shell.rst using nodal_stress() and element_stress(). Inspect how these entry points select SHELL181 stress results and compare their output with the APDL top and bottom values. Done means both top and bottom nodal or element stresses can be retrieved distinctly.

Written by the indexing model from the issue text.