关于修改物料信息的问题

各位老师好:
明明填写了FCategoryID,但还是提示存货类型为必填字段,是什么原因呢?
{
"Result": {
"ResponseStatus": {
"ErrorCode": 500,
"IsSuccess": false,
"Errors": [
{
"FieldName": "FCategoryID",
"Message": "字段“存货类别”是必填项",
"DIndex": 0
},
{
"FieldName": "FCategoryID",
"Message": "编码为“001”的物料，存货类别为必录项！",
"DIndex": 0
},
{
"FieldName": "FNumber",
"Message": "编码为001的物料，编码唯一",
"DIndex": 0
}
],
"SuccessEntitys": []
},
"Id": ""
}
}

构建字符串如下:
{
"Creator": "BAH",
"NeedUpDateFields": [
"FID",
"FNumber",
"FName",
"FCategoryID"
],
"Model": {
"FMATERIALID": 0,
"FNumber": "001",
"FName": "CMU128,STRIP BUTTON,PC,GEN+SIL",
"FMnemonicCode": "141230301129017",
"FMaterialSRC": "A",
"FGEModifyDate": "",
"FGEModifierId": "Administrator",
"BD_MATERIAL__SubHeadEntity": {
"FSAPTYPEID": {
"FNumber": "ROH",
"FName": "ROH"
},
"FSAPUNITID": {
"FNumber": "EA",
"FName": "EA"
},
"FCategoryID": {
"FNumber": "CHLB01_SYS"
},
"FBaseUnitId": {
"FNumber": "Pcs"
},
"FErpClsID": "1"
}
}
}