Report excecution error: net.sf.jasperreports.engine.fill.JRExpressionEvalException: Error evaluating expression for source text: $F{service_name}?

[mjmapi]

Hi Guys,

I'm having problem with this error when i run my report.

My setup includes a main report which has two sub reports in it , when i run this report on PROD/Server i get this error however this report runs fine when i run it on Deleveloper/Studio, when i upload and run each of the reports seperately on the server they run fine without any issues, 

Anyone else experianced?, some guides i have seen online made mention of a 'Null', i have made a provision to cater for this on my scripts/fields with no success

Any pointers??

Regards,

Meli