I understand but I can't read the other side's mind and anything we say would be a guess.
Here is a list of some of the reasons from https://legaldictionary.net/motion-to-dismiss/
Lack of Subject Matter Jurisdiction
The court in which the lawsuit was filed does not have jurisdiction, or the authority, to rule on the matter at hand. For example, a suit requesting enforcement of a child support order cannot be heard in small claims court.
Lack of Personal Jurisdiction
The court does not have the authority to rule on matters that affect one or all of the parties. For example, if Bob is in a car accident in Florida, and the other party involved in the accident files a lawsuit in California, the court would not be able to hear the case.
Improper Venue
The court, or “venue,” in which the matter has been fined is the wrong court to hear the case. For example, Amanda’s accountant, Charlie, siphoned money out of her account for his personal use. Charlie is charged with the crime of embezzlement in criminal court. Amanda wants to sue Charlie for her financial losses, but the criminal court cannot hear that part of the case, as it is not the proper venue. Amanda must file a lawsuit in civil court for damages related to the crime.
Failure to State a Claim for Which Relief Can be Granted
If the plaintiff fails to provide sufficient facts to, if taken on face value as being true, indicate that the defendant violated a law, or caused harm or loss due to negligence, he has failed to state a claim for which relief can be granted. In other words, if the complaint does not clearly say what the defendant did wrong, the court cannot grant any form of relief, and so the case does not need to be heard. For example, there is a company policy that employees greet one another in a friendly manner at work. Joe files a lawsuit claiming that Bob failed to say hello in passing. Bob can file a Motion to Dismiss, as failing to greet another person is not illegal, therefore there is no claim for which relief can be granted.
Insufficient Service of Process
According to the law, a copy of the Summons and Complaint must be personally delivered to the defendant. This is referred to “service of process,” and may be done by a registered process server, the sheriff’s department, or a Constable. In most jurisdictions, service of process may also be accomplished by an individual over the age of majority, who is not involved in the case. Personally delivering the lawsuit to the defendant ensures he or she has been notified of the lawsuit, and has an opportunity to provide an answer to the complaint. A sworn, written statement of when, where, and how the documents were delivered must be filed with the court. In the event the defendant is not properly served, he or she can file a Motion to Dismiss based on insufficient service of process.
Passing of Statute of Limitations
Each state has a statute of limitations, which is a set timeframe in which a plaintiff has to file a lawsuit. The timeframes vary by the type of case, as well as by jurisdiction. In any case, if the statute of limitations timeframe has expired, the plaintiff no longer has grounds to sue the defendant.
For example, if state law requires a plaintiff to bring a negligence case within two years of the date of the injury, and the plaintiff waits two years and two weeks, the defendant can file a Motion to Dismiss, asking the entire case be thrown out. If the court grants the motion, the plaintiff cannot be granted relief on the matter.