Reading DB from S7-318

Reading DB from S7-318

I am running Zenon 6.51, I have a connection to an S7-318 using the S7TCP32 driver and can sucessfully connect to one DB but not another.
For example when I create a variable and address it to DB220.DBX760.7 I can view the data with no problem and if I right click on an element using the variable it shows the status as "spontaneous".
If I create a variable DB226.DBX76.0 then in runtime the status box is displayed and on right click the status is "Invalid".
Monitoring the plc I can see the variable data change but not in the zenon project.
It seems to be an issue with this one DB, has anyone got any suggestions please

This is a migrated post! Originally posted on 06.05.2015 by user allyd. Please be aware that information can be outdated.