AssetsApi.getAssets(searchString) not working

Hi,
when I run a getAssets query manually it works. When I run it via the Java driver it fails with the following errors:

09-29 09:02:00.136: W/System.err(4511): com.google.gson.JsonSyntaxException: java.lang.IllegalStateException: Not a JSON Array: ""
09-29 09:02:00.136: W/System.err(4511): at com.google.gson.Gson.fromJson(Gson.java:900)
09-29 09:02:00.136: W/System.err(4511): at com.google.gson.Gson.fromJson(Gson.java:853)
09-29 09:02:00.136: W/System.err(4511): at com.google.gson.Gson.fromJson(Gson.java:802)
09-29 09:02:00.136: W/System.err(4511): at com.google.gson.Gson.fromJson(Gson.java:774)
09-29 09:02:00.136: W/System.err(4511): at com.bigchaindb.util.JsonUtils.fromJson(JsonUtils.java:133)
09-29 09:02:00.136: W/System.err(4511): at com.bigchaindb.api.AssetsApi.getAssets(AssetsApi.java:37)

09-29 09:02:00.137: W/System.err(4511): Caused by: java.lang.IllegalStateException: Not a JSON Array: ""
09-29 09:02:00.137: W/System.err(4511): at com.google.gson.JsonElement.getAsJsonArray(JsonElement.java:107)
09-29 09:02:00.137: W/System.err(4511): at com.bigchaindb.json.strategy.AssetsDeserializer.deserialize(AssetsDeserializer.java:31)
09-29 09:02:00.137: W/System.err(4511): at com.bigchaindb.json.strategy.AssetsDeserializer.deserialize(AssetsDeserializer.java:21)
09-29 09:02:00.137: W/System.err(4511): at com.google.gson.internal.bind.TreeTypeAdapter.read(TreeTypeAdapter.java:69)
09-29 09:02:00.137: W/System.err(4511): at com.google.gson.Gson.fromJson(Gson.java:888)

The call I use is

AssetsApi.getAssets(searchString)

Thanks,

Alex