I get the following error message after using the sysfit package's function 'systemfitClassic':

Error in data[[eqnVar]] : subscript out of bounds

When I do this:

MSYS1 <- cbind(Y, Num, F, PO, PD, GO, GD)
MigOLS1 <- systemfitClassic("OLS", F ~ PO + PD + GO + GD, eqnVar = "Num", timeVar = "Y", data = MSYS1)
and I get this error message: 

Error in inherits(x, "factor") : attempt to select more than one element

when I do this (removing quotes from columns set as 'eqnVar' and 'timeVar'):

MSYS1 <- cbind(Y, Num, F, PO, PD, GO, GD)
MigOLS1 <- systemfitClassic("OLS", F ~ PO + PD + GO + GD, eqnVar = Num, timeVar = Y, data = MSYS1)

When I query 'typeof()' I get the following:

Y: Integer
Num: Integer
F: Integer
PO: Integer
PD: Integer
GO: Double
GD: Double

I have set my data up in a manner analogous to that in the examples in the systemfit documentation.  Also, the panel is balanced.  If it matters, here are some descriptions of the data:

Y: Year
Num: ID of Flow
F: Flow
PO: Origin Population
PD: Destination Population
GO: Origin GDP
GD: Destination GDP
	[[alternative HTML version deleted]]