Having some trouble incrementing counters
Make CTR static or place it in the global scope. As it stands you set it to 0 every time you go through loop.

The line:

int ctr = 0;


literally means "Create a new variable on the stack called 'ctr' and give it the value 0", and that happens every time loop() is executed.

Instead making it static will change it so that it only happens the first time loop() is executed so it retains its value across successive executions of loop().

static int ctr = 0;