calculating fields

I have searched through the forums and found a few posts regarding calculating fields, I have tried these and cannot seem to make them work for me!

I have 6 fields which I need to add up and the total displayed in the 7th field. Should this work:


oppo_c_sostotal
.value
=oppo_c_strengthofsalecollabora+oppo_c_strengthofsalecrta+oppo_c_strengthofsalepower+oppo_c_strengthofsalepain+oppo_c_strengthofsalevision+oppo_c_strengthofsalevalue

It does not seem to work for me....is there something obvious i am doing wrong??

Thanks