Consider this code:
```
var dropDown = sheet.DataValidations.AddListValidation(cells[2, colIndex, maxCol, colIndex].Address);
foreach (var bb in brokerBranchs)
{
dropDown.Formula.Values.Add(bb.Title);
}
```
When dropDown count is 29 all thing is ok but when greater than 29 i get error
```
var dropDown = sheet.DataValidations.AddListValidation(cells[2, colIndex, maxCol, colIndex].Address);
foreach (var bb in brokerBranchs)
{
dropDown.Formula.Values.Add(bb.Title);
}
```
When dropDown count is 29 all thing is ok but when greater than 29 i get error
