Anyone tell me why this Coldfusion code aint working ?
I built the system on the Coldfusion 9 developer server locally then uploaded it to a Coldfusion 8 hosted server and I get this strange error.

Error can be seen here:$sitepreview/

Code where error is highlighed can be seen here:

Database design can be seen here:

Hmm :/ is there something different about how coldfusion 9 and 8 work with times .. its not even a variable with time in it.

I also tried this code on a locally hosted railo server and it worked fine.

its not even a variable with time in it.
<cfset ET = timeformat(EndTime, 'H')>

Then why are you using timeFormat on it? :) If EndTime is null, its probably returning an empty string, hence the error when you try and perform subtraction. Make sure it's a number and problem solved.

<cfset ET = "">
   <cfset thisFails = ET - 1>