Cannot Convert Char To Money

I've been trying to solve this problem or just find an alternative to do this. I have filled a temp table with certain values for all columns except those columns that rely on calculations that need certain cell values from other columns in the temp table. I have a while statement that runs through each cell for one calculation column and this is the code that updates the fields on the calc column:




Code Block
EXEC('UPDATE #tblTemp
SET #tblTemp.['+@CalcColumns+'] = (CAST(ISNULL((SELECT #tblTemp.['+@Column1+']
FROM #tblTemp
WHERE #tblTemp.PK = '''+@PubKey+'''), 0.00)as money) - CAST(ISNULL((SELECT #tblTemp.['+@Column2+']
FROM #tblTemp
WHERE #tblTemp.PK = '''+@PubKey+''') , 0.00)as money))
WHERE #tblTemp.PK = '''+@PubKey+'''')





The problem is that it will not let me convert the two values to money. The error is:


Msg 235, Level 16, State 0, Line 1

Cannot convert a char value to money. The char value has incorrect syntax.

This is necessary to calculate the difference between these two cells from the temp table. I would appreciate any help! Thanks!