看错误是类型转换错误，看下 fullName 的值是什么？是个报表的路径？
我这边拿你这段代码测试了下，没有问题，代码如下，可以参考下：

import java.io.File;
import java.io.FileInputStream;

import com.raqsoft.dm.Sequence;
import com.raqsoft.report.model.ReportDefine;
import com.raqsoft.report.usermodel.Context;
import com.raqsoft.report.usermodel.Engine;
import com.raqsoft.report.usermodel.IReport;
import com.raqsoft.report.util.ReportUtils;
import com.raqsoft.report.view.excel2007.Excel2007Report;
public class testbb {

	/**
	 * @param args
	 * @throws Throwable 
	 */
	public static void main(String[] args) throws Throwable {
		// TODO Auto-generated method stub
		
		
		File fraq = new File("F:/baogao/20191231.xml"); 
		FileInputStream lis = new FileInputStream(fraq); 
		Sequence.readLicense( Sequence.P_RPT, lis);
String fullName="F:/baogao/基本经营表.rpx";
		ReportDefine rd = (ReportDefine) ReportUtils.read(fullName);
Context cxt=new Context();
		Engine engine = new Engine(rd, cxt); // 构造报表引擎
		IReport iReport = engine.calc(); // 运算报表 
		Excel2007Report er = new Excel2007Report ();


		er.createBigSheet("test",iReport);
		er.saveTo("F:/f.xlsx");
		System.out.println("aaaaaa");
		
	}

}