Why many BI implementations across organizations fails?

# Failure to tie the Business Intelligence Strategy with the Enterprise vision & Strategy.
# Failure to have a flexible BI Architecture that aligns with the Enterprise I.T Architecture.
# Failure to have Enterprise vision of Data Quality, Master Data Management, Metadata Management, Portalization ..etc
# Business Adoptability.
# Various BI tools seamless integration.
# Over-all Business pattern as well as technology is changing. (Example, envisioning DW 2.0 as well as the Business need while architecting)
# Calculating the ROI for any BI implementation and realization takes little longer as compared to other programs.
# Failure due to projects being driven by I.T instead of the business.
# Failure due to business not being involved heavily right from the beginning.
# Lack of good understanding of the BI and Data Warehousing fundamentals and concepts.
# Failure by deviating from the objective and focus during the phases of BI project.
# Lack of BI skills in team implementation team.
# Failure to have a clear working process between the Infrastructures, ETL & Reporting team.
# Lack of continuous support & direction from the leadership team.
# Lack of a clear and detailed BI strategy and road map.
# Failure to gather complete requirements and do system study.
# Lack of a clear understanding of the end goal.
# Lack of a an end to end understanding of the initiative with the source systems team, Infrastructure team, ETL team, Reporting & Analytics team and the Business all functioning in silos.
# Lack of continuous training for the implementation team and the business.
# Lack of a clear support structure.
# Lack of enough budgets that delays upgrades and feature enhancements.
# Implementation of BI plans, direction and work structure by a PMO or Business team without the involvement or consultation of the BI team.
# Lack of clear testing by the UAT team.
# Incorrect and non-flexible data model.
# Lack of clear communication and co-ordination issues between different teams and to the business stake holders.
# Lack of a proper change management process.
# Failure to have a scope creep and breaking the deliverable into phases as there is never an end to the requirements sometimes as BI is iterative and business expects constant delivery of values.
# Failure to include performance criteria as part of the BI and Analytics deliverable.
# Failure to determine and include SLA's for each piece of the BI.