in TESTLAB , for individial test instance inside a test set, there's a user defined Field.

That user defined field is a dropdown(Combobox) if i want to set the value of each test instance manually.

When i try to set that user defined field by vbscript, the code i have used is
tcase(j).Field("TC_USER_47")="BRA SCTL (724-15)"

where tcase is an object of type TSTest

Although the value i am trying to set is present in the dropdown , i get an error saying

"Field <Network Operator> requires a value from the corresponding list"

can anyone please help me on this.