Hey all I am trying to get my cell to vertical line instead of just being aligned by the left side using POI.

This is my java code:
Code:
static CellStyle headerCellStyle    = workbook.createCellStyle();

headerCellStyle = workbook.createCellStyle();
Row headerRow   = null;        
sheet           = workbook.createSheet("String " + sheetname);

headerCellStyle.setWrapText(true);
headerCellStyle.setAlignment(HorizontalAlignment.LEFT);
headerCellStyle.setFillPattern(FillPatternType.SOLID_FOREGROUND);
headerCellStyle.setVerticalAlignment(VerticalAlignment.MIDDLE);

// Create a Row
headerRow   = sheet.createRow(0);
However, the line headerCellStyle.setVerticalAlignment(VerticalAlignment.MIDDLE); has an error of:

The method setVerticalAlignment(org.apache.poi.ss.usermodel.VerticalAlignment) in the type CellStyle is not applicable for the arguments (org.apache.poi.sl.usermodel.VerticalAlignment)

How can i go about getting this to work if I have already defined it as an static CellStyle headerCellStyle = workbook.createCellStyle();?