Hi all,I am trying to create timeline entry via API. This is what I have created, but it fails and gives me the error which I have attached here

{"requests": {"record": {"referenceId": "1",
"TypeName": "Update",
"ExternalId": "{{ExternalId}}",
"Subject": "{{Subject}}",
"Notes": "{{Notes}}",
"Author": "{{Author}}",
"companyName":"{{companyName}}",
"ContextName": "Company",
"ActivityDate":"{{ActivityDate}}"
}}],
"lookups": {"AuthorId": { "fields": {"Author": "Email"},"lookupField": "Gsid","objectName": "GsUser","multiMatchOption": "FIRSTMATCH","onNoMatch": "ERROR"}
,"GsCompanyId": {"fields": {"companyName": "Name"}, "lookupField": "Gsid",  "objectName": "Company",  "multiMatchOption": "FIRSTMATCH",  "onNoMatch": "ERROR"}
}}