KQL - let statement - get an error : No tabular expression statement found

Change the last lines to:

by Computer, bin(TimeGenerated, 1h));
Procdata


You would get the same result with:

let startTime = ago(1d);
let endTime = now();
Perf
| where TimeGenerated between(startTime .. endTime)
| where CounterName == "% Processor Time"
| where ObjectName == "Processor"
| where InstanceName == "_Total"
| summarize PctCpuTime = avg(CounterValue)
by Computer, bin(TimeGenerated, 1h)