Error when extending the web service timeout.

I am using the NWAdmin command line tool to extend the web service timeout and am encountering an issue whereby a command to set the timeout to below the default works: 

 NWAdmin.exe –o SetCallWebServiceTimeout –milliseconds 90000

However, a call to increase it or set it to anything over 90000 results in an error: "milliseconds must be a positive integer.".

 NWAdmin.exe –o SetCallWebServiceTimeout –milliseconds 95000

NWAdmin.exe –o SetCallWebServiceTimeout –milliseconds 100000

NWAdmin.exe –o SetCallWebServiceTimeout –milliseconds 150000

all result in "miliseconds must be a positive integer".

Am I doing something wrong, am I encountering a limitation or is this a bug?

The problem I am trying to solve is that the first web service call of the day results in a timeout. I am using web services to kick off a workflow from a workflow in a single zone host named site deployment with Forms Based Authentication enabled.  So, the first workflow of the day fails.  

Thank you for your help with this!