how to generate a coco Dataset by this tool，I try several times and it doesnot work

[yasuoll]

first, I already have an coco Dataset I made it myself，and it was generated by labelme without tricks,the verson is 5.0.1.(it has label format and coco format both and can workes well during trainning(1500 pictures and json file,size is 23MB) )
then，300 pictures and its json file was generated by this tool ,the next step is to generate a coco format dataset by those pictures and its json file. However ,when I merge json files together(total 1500 + 300)， ONECASE:it says:This JSON file (E:/1537-1833/1542.json) may be incompatible with current labelme. version in file: 0.2.11, current version: 5.1.And the jsonfile' size that generated is only 3MB,and I use it to train my model,it replys that only 300 pictures in my train dataset. TWOCASE: the generated jsonfile only has four Bounding box coordinates without several segementation coordinates. How to generate a coco dataset by those json files?