Cannot perform "tap"

Hi ,
I’m trying to perform a tap and it’s doesn’t work for me.
using java_client 2.1.0
IOS 8.1 (simulaor)

the log is :

info: [debug] Got result from instruments: {"status":0,"value":{"origin":{"x":25,"y":443},"size":{"width":94,"height":25}}}
info: [debug] Pushing command to appium work queue: "target.touch([{\"touch\":[{\"x\":72,\"y\":455.5}],\"time\":0.2},{\"touch\":[{\"x\":72,\"y\":455.5}],\"time\":3.2}])"
info: [debug] Sending command to instruments: target.touch([{"touch":[{"x":72,"y":455.5}],"time":0.2},{"touch":[{"x":72,"y":455.5}],"time":3.2}])
info: [debug] [INST] 2015-03-19 09:40:23 +0000 Debug: Got new command 5 from instruments: target.touch([{"touch":[{"x":72,"y":455.5}],"time":0.2},{"touch":[{"x":72,"y":455.5}],"time":3.2}])

info: [debug] [INST] 2015-03-19 09:40:23 +0000 Debug: evaluating target.touch([{"touch":[{"x":72,"y":455.5}],"time":0.2},{"touch":[{"x":72,"y":455.5}],"time":3.2}])
info: [debug] [INST] 2015-03-19 09:40:23 +0000 Debug: target.touch(__NSCFArray)

but if I’m using the inspector’s Precise tap oprion it does work , and the log is :

info: --> POST /wd/hub/session/c735b07e-4ff5-4766-a45e-8cd069e89d8b/execute {"script":"mobile: tap","args":[{"y":112,"touchCount":1,"x":86,"tapCount":1,"duration":0.6}]}

info: [debug] Pushing command to appium work queue: "au.complexTap({\"tapCount\":1,\"touchCount\":1,\"duration\":0.6,\"x\":86,\"y\":112})"
info: [debug] Sending command to instruments: au.complexTap({"tapCount":1,"touchCount":1,"duration":0.6,"x":86,"y":112})
info: [debug] [INST] 2015-03-19 09:42:57 +0000 Debug: Got new command 34 from instruments: au.complexTap({"tapCount":1,"touchCount":1,"duration":0.6,"x":86,"y":112})
info: [debug] [INST] 2015-03-19 09:42:57 +0000 Debug: evaluating au.complexTap({"tapCount":1,"touchCount":1,"duration":0.6,"x":86,"y":112})
info: [debug] [INST] 2015-03-19 09:42:57 +0000 Debug: target.tapWithOptions({x:"86", y:"112"}, {touchCount:"1", tapCount:"1", duration:"0.6"})
info: [debug] [INST] 2015-03-19 09:42:58 +0000 Debug: evaluation finished

Any idea why it doesn’t work ? (Appium’s bug ?)