我想从这个方程中得到一个值

--counted gives the total row count in a file
samplecount = counted*(10/100);

如何根据这一点采样数据

--Load data
examples = LOAD '/home/sreeveni/myfiles/PE/USCensus1990New.csv' ;

--Group data
groupedByUser = group examples all;

--count no of lines in the file
 counted = FOREACH groupedByUser generate COUNT(examples) ;

--sampling
sampled = SAMPLE examples counted*(10/100);
store sampled into '/home/sreeveni/myfiles/OUT/samplesout';

显示上一行中的错误
无效的标量投影：已计数：需要从关系投影列才能将其用作标量
请给我建议。
我做错什么了吗。