# copy formula not working

In Calc 5.3.2.2 (Xubuntu 16.04), I have a spreadsheet containing two sheets. One of the sheets contains a row of cells containing a formula with absolute references that displays the totals for a given month extracted from the other sheet.

The formula to get the totals for March (ie. month = 3) is: `{=SUM(IF(MONTH(2017_Itemised.H3:2017_Itemised.H1048576)=3,2017_Itemised.I3:2017_Itemised.I1048576,0))}`

I realised that the total for April was displaying 0.0 despite valid values for April being in the '2017_Itemised' sheet.

I tried copying and pasting the formula from the formula bar for 'March' into 'April', but in selecting the formula bar the brace characters { and } disappear, so the resulting formula is: `=SUM(IF(MONTH(2017_Itemised.H3:2017_Itemised.H1048576)=4,2017_Itemised.I3:2017_Itemised.I1048576,0))`

I then tried manually editing the formula in the formula bar to insert the braces, but the cell then just displays the formula string as text without calculating anything.

I have no idea what is going on here. The formula works for every other cell except this one, but as far as I can see the cells are identically configured in every way. Is there some special way to copy such a formula to another cell to make it work?