I think you're right about syntax, because when I tried to add Nihilus instead of Mon Mothma it works! So I' try to find this little mistake. Thanks

1 hour later...
Yes, I've finally edited it and now it works like an another hero! But I still don't know where the mistake was, I've just recoded all the sandboxes again
And there is another one problem:
When lightsaber is off:

but when it is on,

I've copy this from Darth Vader unit(because Nihilus has the same bones and animation, but his lightsaber is longer):
<!-- Lightsaber holstering data -->
<SFXEvent_Draw_Weapon> Unit_Light_Saber_On </SFXEvent_Draw_Weapon>
<SFXEvent_Holster_Weapon> Unit_Light_Saber_Off </SFXEvent_Holster_Weapon>
<Holster_Weapon_Bone_Name> b_saber </Holster_Weapon_Bone_Name>
<Holster_Drawn_Bone_Translation> 0.0, 0.0, 0.0 </Holster_Drawn_Bone_Translation>
<Holster_Holstered_Bone_Translation> 0.0, 4.835, 0.0 </Holster_Holstered_Bone_Translation>
<Holster_Transition_Time_In_Secs> 0.17 </Holster_Transition_Time_In_Secs>
<Holster_Minimum_Drawn_Time_In_Secs> 15.0 </Holster_Minimum_Drawn_Time_In_Secs>
<Holster_Disable_Engine_Loops> Yes </Holster_Disable_Engine_Loops>
but Darth Vader's lightsaber looks normal when it is off...
Why?