GestureNet build engine error

I am using the pre-trained model of GestureNet from NGC. I have two files[model.etlt and labels.txt].
Following is the config file parameters:

[property]
gpu-id=0
net-scale-factor=0.0039215697906911373
model-color-format=0

labelfile-path=./labels.txt
tlt-encoded-model=./model.etlt
tlt-model-key=tlt_encode
input-dims=3;160;160;0
uff-input-blob-name=input_1
batch-size=4

0=FP32, 1=INT8, 2=FP16 mode

network-mode=0
num-detected-classes=6
interval=0
gie-unique-id=1
is-classifier=1
operate-on-gie-id = 1
operate-on-class-ids=1

output-blob-names= output_cov/Sigmoid;output_bbox/BiasAdd

[class-attrs-all]
pre-cluster-threshold=0.1
group-threshold=1
eps=0.2
roi-top-offset=0
roi-bottom-offset=0
detected-min-w=0
detected-min-h=0
detected-max-w=0
detected-max-h=0

As I have googled, I am suspecting the output-blob-name as the point of error but don’t know what else to put in place of that.
I am getting build engine fail error every time, can someone tell me what is going wrong??

Refer to
How to find the input/output layers names of tlt/etlt model - #7 by Morganh and
How to find the input/output layers names of tlt/etlt model - #8 by Morganh