Make sure you copy-paste the GATC directly from your GA account into the Code of your web pages. This will ensure there is no alteration to the GATC formatting.
Avoid copying the GATC from a tool like MS word because it can attach extra spaces or modify quotation marks to your tracking code. As we mentioned, extra spaces or additional characters such as extra comma, brackets, or semicolons can prevent your GATC from starting at the time of page loading.