What is the exact name of the table held in SQL Server?
If it's my_long_name_table_Tas, then you should use
new CustomPluralizationEntry("my_long_name_table_Tas", "my_long_name_table_Tas")
If it's my_long_name_table_Tas, then you should use
new CustomPluralizationEntry("my_long_name_table_Tas", "my_long_name_table_Tas")