Here's why:
* "Will be" is the future tense of the verb "to be".
* "Had" is the past participle of the verb "to have".
You cannot combine these two forms directly.
Here are some ways to use "will be" and "had" correctly:
* "Will have been": This is the future perfect tense, indicating an action that will be completed before a specific time in the future. Example: "By tomorrow, I will have been working here for a year."
* "Will have had": This is the future perfect tense of the verb "to have". Example: "By next month, I will have had my birthday."
To use "had" correctly, you'd need to use it with the past tense of "be" (was/were). For example:
* "He was had" (meaning he was tricked or fooled)
* "They were had" (meaning they were tricked or fooled)
If you're trying to express a future action or state, you need to rephrase your sentence to use the correct tense and verb forms.