Error message when importing mesh?

I had to fix the shadow of my mesh, but when I try to import the Blender file, it gives me this message:

----------------------------------
The Sims 4 Studio - Version 3.1.4.5

System.AggregateException: One or more errors occurred. ---> S4Studio.Blender.BlenderException:

File "<string>", line 1, in <module>

File "<string>", line 17, in <module>

File "C:\Users\User\AppData\Roaming\Blender Foundation\Blender\2.70\scripts\addons\s4studio\io.py", line 626, in write

rcol.get_block_index(self, self.ROOT_REFERENCE_TYPE)

File "C:\Users\User\AppData\Roaming\Blender Foundation\Blender\2.70\scripts\addons\s4studio\io.py", line 525, in get_block_index

block.write_rcol(stream, self)

File "C:\Users\User\AppData\Roaming\Blender Foundation\Blender\2.70\scripts\addons\s4studio\buybuild\geometry.py", line 346, in write_rcol

for mesh in self.meshes: mesh.write(stream, rcol)

File "C:\Users\User\AppData\Roaming\Blender Foundation\Blender\2.70\scripts\addons\s4studio\buybuild\geometry.py", line 188, in write

s.u32(rcol.get_block_index(self.material))

File "C:\Users\User\AppData\Roaming\Blender Foundation\Blender\2.70\scripts\addons\s4studio\io.py", line 525, in get_block_index

block.write_rcol(stream, self)

File "C:\Users\User\AppData\Roaming\Blender Foundation\Blender\2.70\scripts\addons\s4studio\model\material.py", line 318, in write_rcol

s.u32(rcol.get_block_index(state.material))

File "C:\Users\User\AppData\Roaming\Blender Foundation\Blender\2.70\scripts\addons\s4studio\io.py", line 525, in get_block_index

block.write_rcol(stream, self)

File "C:\Users\User\AppData\Roaming\Blender Foundation\Blender\2.70\scripts\addons\s4studio\model\material.py", line 254, in write_rcol

self.material_block.write(material_block_stream, rcol)

File "C:\Users\User\AppData\Roaming\Blender Foundation\Blender\2.70\scripts\addons\s4studio\model\material.py", line 71, in write

item.write_pointer(stream)

File "C:\Users\User\AppData\Roaming\Blender Foundation\Blender\2.70\scripts\addons\s4studio\model\material.py", line 108, in write_pointer

t = type(self.value[0])

IndexError: list index out of range





at S4Studio.Blender.BlenderUtilities.RunBlender(String script, String blend, Boolean background, Boolean check_version)

at S4Studio.Blender.BlenderUtilities.ImportMlod(String fileName, String mlod, String rig, String state)

at S4Studio.ViewModels.ObjectLodItem.ImportMesh(BlenderUtilities blender_util, String blender_path)

at S4Studio.ViewModels.ObjectLodItem.<>c__DisplayClass49_0.<ImportMesh>b__0()

at System.Threading.Tasks.Task.InnerInvoke()

at System.Threading.Tasks.Task.Execute()

--- End of inner exception stack trace ---

---> (Inner Exception #0) S4Studio.Blender.BlenderException:

File "<string>", line 1, in <module>

File "<string>", line 17, in <module>

File "C:\Users\User\AppData\Roaming\Blender Foundation\Blender\2.70\scripts\addons\s4studio\io.py", line 626, in write

rcol.get_block_index(self, self.ROOT_REFERENCE_TYPE)

File "C:\Users\User\AppData\Roaming\Blender Foundation\Blender\2.70\scripts\addons\s4studio\io.py", line 525, in get_block_index

block.write_rcol(stream, self)

File "C:\Users\User\AppData\Roaming\Blender Foundation\Blender\2.70\scripts\addons\s4studio\buybuild\geometry.py", line 346, in write_rcol

for mesh in self.meshes: mesh.write(stream, rcol)

File "C:\Users\User\AppData\Roaming\Blender Foundation\Blender\2.70\scripts\addons\s4studio\buybuild\geometry.py", line 188, in write

s.u32(rcol.get_block_index(self.material))

File "C:\Users\User\AppData\Roaming\Blender Foundation\Blender\2.70\scripts\addons\s4studio\io.py", line 525, in get_block_index

block.write_rcol(stream, self)

File "C:\Users\User\AppData\Roaming\Blender Foundation\Blender\2.70\scripts\addons\s4studio\model\material.py", line 318, in write_rcol

s.u32(rcol.get_block_index(state.material))

File "C:\Users\User\AppData\Roaming\Blender Foundation\Blender\2.70\scripts\addons\s4studio\io.py", line 525, in get_block_index

block.write_rcol(stream, self)

File "C:\Users\User\AppData\Roaming\Blender Foundation\Blender\2.70\scripts\addons\s4studio\model\material.py", line 254, in write_rcol

self.material_block.write(material_block_stream, rcol)

File "C:\Users\User\AppData\Roaming\Blender Foundation\Blender\2.70\scripts\addons\s4studio\model\material.py", line 71, in write

item.write_pointer(stream)

File "C:\Users\User\AppData\Roaming\Blender Foundation\Blender\2.70\scripts\addons\s4studio\model\material.py", line 108, in write_pointer

t = type(self.value[0])

IndexError: list index out of range





at S4Studio.Blender.BlenderUtilities.RunBlender(String script, String blend, Boolean background, Boolean check_version)

at S4Studio.Blender.BlenderUtilities.ImportMlod(String fileName, String mlod, String rig, String state)

at S4Studio.ViewModels.ObjectLodItem.ImportMesh(BlenderUtilities blender_util, String blender_path)

at S4Studio.ViewModels.ObjectLodItem.<>c__DisplayClass49_0.<ImportMesh>b__0()

at System.Threading.Tasks.Task.InnerInvoke()

at System.Threading.Tasks.Task.Execute()<---

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The problem is not on the Blender file. When I try to import it into a new package, it works.
This problem only happens when I had already imported a new mesh into a file, and I'm trying to import a "second version" into the same file.

Does anyone what it is?

I could simply create a new package using the new edited mesh, but sometimes it's not very practical at all, when you already edited all the other files and swatches on the previous package XD

Thanks.