API call for each row - 400 Bad Request

I have a list of parent ID's generated from an intial API call:

Now I want to call a second API for each row, using each of these parent ID's as inputs, and put it all into one big table. So I made a custom column:

= Web.Contents("https://urlexample.com/webapi/v01.0/eobjects/XMLData/CampaignOpenClickDetails/" & Number.ToText([CampaignID]) & "?pageon=1&pagesize=10", [Headers=[#"User-Key"="key", #"Company"="company",#"UserName"="username"]])

 Now I have successfully made the custom column and I get the Binary content link

but when I click on the Binary link to try and expand it, I get this error:

DataSource.Error: WebContents failed to get contents from 'https://urlexample.com/webapi/v01.0/eobjects/XMLData/%0ACampaignOpenClickDetails/126289?pageon=1&pagesize=10' (400) Bad Request
Details:
DataSourceKind=Web
DataSourcePath=https://urlexample.com/webapi/v01.0/eobjects/XMLData/%0ACampaignOpenClickDetails/126289
Url=https://urlexample.com/webapi/v01.0/eobjects/XMLData/%0ACampaignOpenClickDetails/126289?pageon=1&pagesize=10

I know the headers (masked in this example) are correct because I use the exact same headers for the intial API call. Also, I'm able to successfully make this exact API call in Postman, so I know I have network access and such. What am I missing?