BitShares2-light import bts v0.9.3c key error

[marschen]

hi，
I use bts v0.9.3c console command  "wallet_export_keys d:\1.json " export my key.
and then use BitShares2-light import my key with the following problems：
"Key import error:cannot read property "key" of null"

Please tell me how to solve this problem，Thank you！