How to apply counter while creating AMI image

I am writing the script to create images of the running instances and the instance have the tags of Retention Count and Frequency then the value will be picked from that running instance otherwise it will set the default value provided. Number of images created will depend on frequency.

but I am getting this output.

I have set the Frequency to in the script and I have applied the counter but instead of incrementing the value of count, it is giving the same value. For now the retention count may be dropped as I am not using this till now.