Sum column based on if date is between two dates

Hi there,

I have the following tables, and i am trying to count the number of rows in 'Table 2' where 'Lost' = 1 and the data in 'Table 1' is the same month. I am trying to do this by adding a custom column to 'table 1' using DAX.

Table 1 - Example

MMYYDD = end of month

Table 2 Example:-

Example of data from Table 2

I am hoping to achieve the following in 'Table 1' by adding a calculated column called 'Lost':-

Any ideas or help greatly appreciated!

CF