Using an expression to populate a label

I have a label that I would like to show a setpoint and actual value, thusly:


I tried building an expression in stages. The first step was
{cntBottling.dsTankFlowData}[“FlowSet1”]+’ / ’
which worked fine.
When I tried
{cntBottling.dsTankFlowData}[“FlowSet1”]+’ / '+{cntBottling.dsTankFlowData}[“FlowSet1”]
in a test to try and concatenate two numbers, I got the error
"Type mismatch in operation ‘Dataset Subscript’ expected ‘Dataset’, found ‘String’.

Please advise.



({cntBottling.dsTankFlowData}["FlowSet1"])+' / '+({cntBottling.dsTankFlowData}["FlowSet1"])