There may be the following reasons for the failure to start the construction of Yangling Happy Garden on time:

1. Epidemic impact: The global COVID-19 epidemic has had a great impact on all walks of life, including Yangling Happy Garden. The epidemic situation led to the closure of the construction site, the inability of workers to be present, transportation restrictions and other problems, which made the project unable to start as planned.

2. Delayed project preparation: In the planning stage, more time and preparation may be needed to ensure the smooth implementation of the project. For example, financing, land requisition, design deepening, bidding and procurement may be delayed for various reasons.

3. Policy adjustment: Government departments may make policy adjustments during the project planning process, which may affect the commencement time of the project. For example, policy changes may lead to the need for re-approval of the original planning and permission, further prolonging the preparation time of the project.

4. environmental protection restrictions: in order to protect the ecological environment, the government may impose restrictions on the construction and operation of some projects. If the project fails to meet the relevant policy requirements in environmental protection, it may need to be re-evaluated and approved, which will also affect the start-up time of the project.

5. Constraints of construction conditions: The geographical location, climatic conditions and site conditions of the project may affect the commencement time of the project. For example, during the construction period, bad weather and complicated geological conditions may be encountered, which may cause the project to fail to start on time.

it should be noted that the specific reasons may vary according to the individual situation of the project. In order to accurately understand the detailed reasons for the delay in the construction of Yangling Happy Garden, it is best to pay attention to relevant official announcements or news reports, or contact relevant departments or investors for consultation.