Java - ESCRIBIR EXCEL CON POI

agrego esta formula usando el api de POI para crear un documento de excel y me aparece un error en la libreria...
SUMA(C11;C12;C13;C14;C15;C16;C17;C18;C19;C20;C21;C22;C23;C24;C25;C26;0)-SUMA(0)
81
Err : String index out of range: 81
java.lang.StringIndexOutOfBoundsException: String index out of range: 81
at java.lang.String.charAt(Unknown Source)
at org.apache.poi.hssf.model.FormulaParser.GetChar(FormulaParser.java:102)
at org.apache.poi.hssf.model.FormulaParser.SkipWhite(FormulaParser.java:176)
at org.apache.poi.hssf.model.FormulaParser.Match(FormulaParser.java:188)
at org.apache.poi.hssf.model.FormulaParser.function(FormulaParser.java:326)
at org.apache.poi.hssf.model.FormulaParser.Ident(FormulaParser.java:266)
at org.apache.poi.hssf.model.FormulaParser.Factor(FormulaParser.java:484)
at org.apache.poi.hssf.model.FormulaParser.Term(FormulaParser.java:558)
at org.apache.poi.hssf.model.FormulaParser.Subtract(FormulaParser.java:593)
at org.apache.poi.hssf.model.FormulaParser.Expression(FormulaParser.java:609)
at org.apache.poi.hssf.model.FormulaParser.parse(FormulaParser.java:710)
at org.apache.poi.hssf.usermodel.HSSFCell.setCellFormula(HSSFCell.java:678)
at org.user.tablemodel.change.FormularioModel.exportExcel(FormularioModel.java:1756)
at org.user.tablemodel.change.FormularioModel.main(FormularioModel.java:276)