Post to Bot from CRM Custom Function

I'm trying to post text to a bot with the code below (from zCRM). It works fine when using "Save & Execute" but will not run when triggered with a workflow.

Scenario:

User creates a quote and a Bot informs user of the Shipping cost.

Any idea why the code will not run when the custom function is triggered within a workflow rule?

My code snippet is:

//Compose msg to post to cliq

msg = "Shipping estimate for Quote #" + quoteNum + " $" + finalShipping;

mp = Map();

mp.put("text",msg);

mp.put("broadcast","false"); //have also tried true here

resp = zoho.cliq.postToBot("devbot",mp);